modul dasar pemrogman tentang fungsi

MEETINGS

A B S T R A C T S O F PAPERS PRESENTED AT

THE 14TH CONFERENCE OF THE WEED SCIENCE
SOCIETY OF I S R A E L
March 13, 1996
ARO, The Volcani Center, Bet Dagan, Israel

A: HERBICIDES: NOVEL PRODUCTS, FORMULATIONS OR COMBINATIONS AND THEIR USE
FOR WEED CONTROL IN VEGETABLES, FIELD CROPS AND ORNAMENTALS
Sulfentrazone - A New Herbicide
E. Yogev, M. Berson and Y. Benyamini

Luxembourg Chemicals and Agriculture Ltd., Tel Aviv 61000, Israel [Fax: +972-3-5100474]
Sulfentrazone (F-6285) is a new herbicide, manufactured by FMC, U.S.A. The product is an aryl
triazolinone, applied to existing weeds as well as pre-emergence. Sulfentrazone is formulated as 75%
w/w water-dispersible granules. It is not volatile, is moderately mobile in the soil, and not sensitive
to UV light. It appears to be relatively persistent in the soil; it is decomposed mainly by microbial
degradation. Sulfentrazone controls weeds by the same mechanism as the diphenyl ethers, in which
membrane disruption is initiated by the inhibition of protoporphyrinogen oxidase in the chlorophyll

biosynthetic pathway, which leads to the subsequent buildup of toxic intermediates. Plants emerging
from soils treated with sulfentrazone absorb the product through the root system, the weeds turn
necrotic and die shortly after exposure to light. When the product is sprayed on existing weeds (foliar
application), it is absorbed by the leaves but the movement in the phloem is limited because of rapid
foliar desiccation.
Sulfentrazone is designed by the manufacturer for the control of weeds in soybeans. In Israel,
the product is being tested in various field crops, in orchards and in turf. In field trials it was found
to be safe to chickpeas, in pre-emergent application at the rate of 430 g a.i./ha. At this rate, the
product prevented emergence of Solanum nigrum, Amaranthus retroflexus, A. blitoides, Polygonum
equisetiforme and Cyperus rotundus for the entire chickpea season, without the necessity of manual
weeding. At 960 g a.i./ha in preplant application, sulfentrazone was safe to cauliflower and cabbage,
and at 1920 g a.i./ha it was safe to citrus seedlings. The product was effective in controlling and
preventing emergence of Malva nicaeensis, Senecio vernalis, Urtica urens, Conyza spp. and other
winter broadleaved weeds. Winter cereals, including Lolium rigidum, Avena sterihs and wheat, were
also controlled by it.
Sulfentrazone was sprayed on commercial turf areas after cuttings of the turf carpets. At the rate
of 960 g a.i./ha it prevented emergence of Portulaca oleracea, Amaranthus viridis and C. rotundus for
a period of more than 90 days after spraying. Sulfentrazone is also being tested in foliar applications
on existing turf, for the control of C. rotundus.
The characteristics of sulfentrazone, including control of existing weeds, preventing emergence

of many widespread winter and summer weeds, long-lasting effect, and its safety to various crops,
reveal a good potential for its use in the future.

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Oxadiargyl (R.E-0206630) - A Selective Pre- and Early Postemergence Herbicide for
Vegetables before Transplantation
Y. Sheinboim, T. Lev-Ran, A. Bahat, Y. Barkai, Y. Gatti, M. Zaidan, O. Barazani and
Y. Boshvize

Agrochemicals Dept., Milchan Bros. Ltd., Ramat Can 52117, Israel [Fax: +972-3-7518103]
Raft (400 g/l S.C.) is the trade name of oxadiargyl, a new Rhfne-Poulenc oxadiazol herbicide. Its
mode of action and range of activity are quite similar to those of oxadiazon (Ronstar) and oxifluorfen
(Goal), which are well known and recommended as standards in Israel. Oxadiargyl is primarily a
pre- but also a postemergence weed killer. Its herbicidal action is much more effective and vigorous
when applied pre-emergence or at early postemergence, on young and actively growing weeds.
Oxadiargyl, applied at a rate of 0.5-0.8 kg/ha, prevented the emergence of susceptible weeds
such as: Malva nicaeensis, Lavatera spp., Urtica urens, Lamium amplexicaule, Amaranthus spp.,

Portulaca oleracea, Sinapis spp., Solanum nigrum, S. villosum, Phalaris spp., Avena sterilis,
Echinochloa spp. and Digitaria sanguinalis for 2-3 months.
Transplanted cabbage, cauliflower, broccoli and tomato in the open field demonstrated very good
tolerance to oxadiargyl at a rate of 0.6 kg/ha, when applied prior to transplantation. Watermelon,
transplanted into the treated mulched beds, tolerated oxadiargyl at rates up to 1.0 kg/ha. The tested
herbicide was applied and activated by rainfall approximately 2 months before transplanting. The
treated area was mulched with polyethylene film one month after the herbicide application. A drip
irrigation system was placed on the beds, just before mulching.
Oxadiargyl, at rates up to 0.8 kg/ha, was found very selective to garlic, when applied pre- or
early postemergence. Sown onion, when treated at the phenological stage of 1 89 leaves, tolerated
oxadiargyl at rates up to 0.5 kg/ha without any yield decrease.
The broad spectrum of activity and the good safety margin make Raft a valuable tool to use with
the standard practices when applied as a pre- or early postemergence treatment before transplanting
vegetables.

Control of Weeds in Tomatoes Grown for Processing in the Golan Heights Region
S. Graph I and U. Luchinsky 2
aExtension Service, Ministry of Agriculture, Zefat 13111 [Fax:+972-6-921021];and 2Mevo
Hamma, Ramat HaGolan 12480, Israel
The incorporation of pendimethalin at 1750 g/ha, 3 months and 2 weeks, respectively, before

transplanting gave good control ofSolanum sp. andAmaranthus sp. However, without incorporation,
this treatment was less effective in Solanum sp. control. The tomato plants were not affected by the
earlier treatment; the 2-week pre-transplanting treatment caused, however, some growth retardation.
In another trial it was found that oxadiazon at 500 g/ha; oxadiargyl at 500 and 1000 g/ha;
oxyfluorfen at 357 g/ha; and pendimethalin at 1750 g/ha were all effective in the control of Solanum
sp., whereas dilufenican was not sufficiently effective at 125 g/ha or even 250 g/ha.
None of the herbicides used in this trial caused any symptoms of injury to the tomato plants.

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Control of Annual Weeds in Transplanted Tomatoes
T. Blumenfeld, Y. Kleifeld, G. Herzlinger, H. Bucsbaum, S. Golan, T. Chilf and R. Aly

Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900, Israel
[Fax: +972-4-9836936]
During 1994 and 1995 we conducted field experiments testing herbicides for control of annual
weeds such as Amaranthus spp., Solarium spp. and Polygonum spp. in transplanted tomatoes.
Preplanting treatments with oxyfluorfen (Goal, 240 g/l, EC) or pendimethalin (Stomp, 500 g/l,

EC) on tomato beds, followed by sprinkler irrigation or rain, usually prevented the emergence of
annual weeds up to the beginning of the drip irrigation. In early transplanting the lower leaves
were damaged by oxyfluorfen, and light to medium damage was observed following pendimethalin
treatments, in loess soils, following hand-planting in cold soil. In a similar application method the
new herbicides flazasulfuron (Lux-40, 250 g/l, WG) and sulfentrazone (F-6285, 480 g/l, SC) were
selective to tomatoes transplanted in loess soil and prevented annual weed infestation at least up to
the application of metribuzin (Lexone, 75%, WG).
In a field experiment in the Golan Heights, fomesafen (Flex, 250 g/l, SL) and diflufenican
(Quartz, 500 g/l, SC) did not damage tomatoes in preplanting treatments. In organic soil in the
Hula Valley, experiments showed that preplanting application of oxadiargyl (Raft, 400 g/l, SC) and
oxyfluorfen controlled Polygonum spp., Chenopodium spp. and weeds belonging to the Cruciferae.

Weed Control in Wheat in Northern Kazakhstan
Y. Ohali
Agrochemicals Department, Milchan Bros. Ltd., Ramat Gan 52117, Israel [Fax: +972-3-7518103]
The northern regions of Kazakhstan, in terms of geomorphology and climate, are an inherent part
of southern Siberia. Temperatures fall to -45~ in winter, and can reach up to +40~ in summer.
Freezing conditions exist generally from October until mid-April. In summer, weather conditions
are unstable and vary greatly from day to day. For example, summer temperatures may range from
30~176 but may drop, from time to time, to below 10~ Precipitation varies between 200 and

400 mm annually, depending on the region and year, mostly as rainfall in summer, and in small
part as snow in winter. Very strong winds prevail in both winter and summer, causing snowdrift
from the fields in winter and desiccating the crops in summer. Over 95% of the wheat fields in
Kazakhstan are grown during the summer; winter wheat has greater yield potential, but involves
a higher risk factor due to freezing of seeds and young seedlings. 'Minimal cultivation' is quite
common in northern Kazakhstan and southern Siberia, mostly for soil preservation reasons. This
aggravates weed infestation, mainly perennial weeds.
The most common perennial weeds are: Compositae: Sonchus arvensis, Cirsium arvensis,
Lactuca tatarica; Convolvulaceae: Convolvulus arvensis; and Euphorbiaceae: Euphorbia sp. The
most common annual weeds are: Amaranthus sp., Chenopodium sp., Polygonum tatarica, Cruciferae
species. The major herbicides in use are the phenoxy compounds, especially of Russian production.
Due to weed resistance to those herbicides which has developed during recent years, Kazakhstani
farmers are searching for additional solutions for weed control. Sulfonylurea products are not
widely used. Applications of a formulation containing chlorsulfuron (Glean) and dicamba (Banvel,
Mediben) are quite limited due to soil residues problems. Triasulfuron (Amber) does not show good
efficacy in controlling Chenopodium sp. Tribenuron-methyl (Express, Granstar) is effective on most

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varieties, but when Convolvulus sp. is the dominant weed, the combination of tribenuron-methyl and
phenoxy compounds (each component at half rate) is the optimal solution.
The main grass weeds in north Kazakhstan are Panicum sp., Setaria sp. and Avena fatua.
Triallate (Avadex BW, Far-go) is the main grass killer due to its relatively low price. Additional
products in but little use are: diclofop-methyl (llloxan), fenoxaprop-ethyl (Puma) and clodinafoppropargyl (Topik).

Snapshot T M 2.5G, a Granular Herbicide for Pre-Emergence Weed Control in
Nursery and Ornamental Flowers and Trees
A. Ovadia, Y. Chachlon, H. Yovel, Y. Tesler and G. Colodney

Tarsis-Agrichem, Tel Aviv 61001, Israel [Fax: +972-3-9243618]
Snapshot TM 2.5G is a granular herbicide containing 2.0% trifluralin, a dinitroaniline, and 0.5%
isoxaben, a benzamide. Snapshot should be dispersed at rates of 100-200 kg/ha in nurseries,
greenhouses and in open fields on pots or on soil surface to prevent annual weeds' emergence.
Trifluralin complements isoxaben's herbicidal activity. Whereas isoxaben is effective in prevention
of broadleaved emergence, trifluralin is effective in preventing emergence of grass weeds and a
variety of broadleaved weeds. Both trifluralin and isoxaben inhibit cell division, and have very low
water solubility (less than 1 ppm) and long residual activity.
Snapshot can be safely applied when the crop is well established or after full blooming.

Dispersing the product right after cutting or before blooming may inhibit or damage the blooming
buds, if some granules are left on the nodes. No phytotoxic damage was observed on existing leaves
in crops. Numerous trials were conducted in crops such as Aspidistra, Hypericum, asparagus and
roses, and in citrus, apple and myrtle nurseries, and others.
The following weeds are susceptible to Snapshot: Cardamine hirsuta, Stellaria media, Conyza

canadensis, Senecio vulgaris, Beta vulgaris, Lactuca serriola, Oxalis corniculata, Euphorbia
prostrata, Urtica urens, Galinsoga parviflora, Fumaria sp., Galium sp., Digitaria sanguinalis,
Setaria verticillata, Oryzopsis miliacea (Piptatherum holciforme) and others.
B: RESISTANCE OF WEEDS TO HERBICIDES AND USE OF SYNERGISM TO CONTROL
RESISTANT AND HARD-TO-KILL WEEDS; BIOASSAY OF HERBICIDES IN SOIL AND WATER

Vegetation Management on Roadsides and at Industrial Sites in Israel
A. Nir
Weed Control Co. Ltd., Bet Dagan 50250, Israel [Fax: +972-3-9663020]
Israel, an east Mediterranean country, has a short and rainy winter season, a mild spring and a
long and arid summer and autumn, Under these conditions most of the winter annual weeds dry up
by mid summer and constitute a serious fire hazard. The main goals achieved by proper vegetation
management along roads and highways are: (i) effective prevention of weed fires; (ii) enhancement
of road traffic safety; (iii) improvement of roadside shoulders safety; and (iv) enhancement of

ditchbanks' soil erosion protection.
The triazine group of herbicides was introduced in the early 1960s. With time and their constant
use, triazine-resistant annual grasses such as Phalaris paradoxa, Lolium rigidum, Alopecurus
myosuroides, Polypogon monspeliensis, Brachypodium distachyon and others, started to prevail.
Trials conducted to find replacement or complementary herbicides yielded good results with
the combinations simazine + metolachlor at 2.5 kg/ha each; simazine + diuron at 2.0 kg/ha each;

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sulfometuron-methyl (alone) at 0.075 kg/ha; and imazapyr (alone) at 0.5 kg/ha. Sulfometuronmethyl gave good control of Sorghum halepense at 0.075 and 0.188 kg/ha but did not affect
Hyparrhenia hirta or Cynodon dactylon, whereas imazapyr at 1.25 kg/ha gave almost 100% control
of these three perennials; imazapyr at 0.625 kg/ha performed only very slightly inferior to the higher
rate.
Former vegetation management programs were described and evaluated in comparison with
recent findings from extensive field trials. An updated review of the latest roadside weed control
recommendations and some thoughts about the future were included.

Characterization of Littleseed Canarygrass (Phalaris minor) Resistance to

Fenoxaprop-ethyl
S. Zarka, A. Tal and B. Rubin
Dept. of Field Crops, Vegetablesand Genetics, The Hebrew University of Jerusalem, Faculty of
Agriculture, Rehovot 76100, Israel [Fax: +972-8-9362083]
In recent years, evolution of resistant graminaceous weeds to aryloxyphenoxypropionate
(AOPP) and cyclohexanedione (CHD) herbicides has been reported frequently from many countries
worldwide. In most cases, resistance is due to the widespread and intensive use of selective
graminicides in cereal crops.
Recently, we discovered in a wheat field in southern Israel a population of littleseed canarygrass
(Phalaris minor) which was poorly controlled by fenoxaprop-P-ethyl (Puma super, 75 g/l EC). Seeds
of the resistant population (R) were collected, tested under controlled conditions, and compared with
a susceptible population (S) collected from nearby untreated fields. The R biotype was found to
be highly resistant to fenoxaprop-P-ethyl and other AOPP and CHD herbicides. The ratios R/S of
the calculated EDso for fenoxaprop-P-ethyl, fenoxaprop-ethyl (Forure, 90 gll EC), diclofop-methyl
(Illoxan, 360 g/l EC) and tralkoxydim (Grasp, 100 g/l EC) were 24, 9, 1.6 and 1.5, respectively.
No differences between the R and S biotypes were found for EDso in the case of haloxyfop-methyl
(Gallant, 125 g/l EC) and clodinafop (Topik, 100 g/l EC). Similarly, no differences between the
biotypes were observed in response to propanil (Stam, 480 g/l EC), methabenzthiazuron (Tribunil,
70% WP) and isoproturone (Tolkan, 50% SC).
To elucidate the mechanism of the resistance, comparative tests of 14C-fenoxaprop-P-ethyl

uptake, translocation and metabolism were carried out. The results indicated that R and S biotypes
did not differ in these parameters. However, the enzyme ACCase (acetyl coenzyme A carboxylase,
the target site of AOPP and CHD) extracted from R plants was less sensitive than the enzyme from S
plants. For example, the 15o (50% enzyme inhibition) in response to fenoxaprop was 20-fold higher
for the R biotype than for the S biotype. This trend of less sensitivity of ACCase from the R biotype
was also detected for other AOPP and CHD herbicides. The close correlation between the wholeplant level (EDso) and the enzyme level (I5o) results, suggests that resistance of littleseed canarygrass
to fenoxaprop-ethyl is conferred by a modification at the target site, i.e., ACCase gene.

Synergy between Flumioxazin and Other Herbicides for Improved Weed Control
T. Yaacoby, 1 A. Tal, 2 Y. Alon, 3 Y. Kedar 3 and B. Rubin 2

1Plant Protection and Inspection Services, Ministry of Agriculture, Bet Dagan 50250
[Fax: +972-3-9681507q; 2Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of
Jerusalem, Faculty of Agriculture, Rehovot 76100; and 3Agan Chemical Manufacturers Ltd.,
Ashdod 77102, Israel
Flumioxazin (S-53482) is a new phenyl-phthalimide herbicide which acts like a diphenylether
by inhibiting protoporphyrin IX synthesis. It was introduced recently by Sumitomo Chemicals for

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203

pre- and postemergence control of annual broadleaved weeds in soybeans and other crops. Pot and
field experiments were conducted in order to examine the synergy between flumioxazin and other
postemergence herbicides. Weeds which require special measures or high rates for their control
were treated at the 3- to 4-leaf stage with a low rate of flumioxazin with and without glyphosate,
triazines, diclofop or fenoxaprop, using a chain-driven sprayer. The combination of very low
rates (1 to 10 g/ha) of flumioxazin with reduced rates of glyphosate (0.5 kg/ha) synergistically
controlled hard-to-kill annual weeds such as Malva spp., Medicago spp. and Urtica urens, which
tolerate the recommended rate of glyphosate applied alone. Similarly, pot and field experiments
demonstrated that combinations of flumioxazin with triazines result in efficient control of triazineresistant biotypes ofAmaranthus hybridus and A. blitoides. In addition, mixtures of flumioxazin and
fenoxaprop effectively overcame fenoxaprop resistance in Phalaris minor. Volunteer wheat was not
injured by the field rates of flumioxazin or diclofop applied alone. However, significant synergistic
effects were observed when the plants were treated with low rates of flumioxazin combined with
dictofop. Furthermore, the combined treatments of flumioxazin with slow-acting herbicides such as
glyphosate, triazines and aryloxyphenoxy propanoates resulted in a unique and rapid necrosis of the
foliage, indicating the major contribution of flumioxazin to the observed synergism.

A Sensitive Bioassay Suitable for Quantitative Estimation of Sulfonylurea Herbicides
in Soil and Water
Orit Ben-Zvi Assaraf and B. Rubin

Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem, Faculty of
Agriculture, Rehovot 76100, Israel [Fax: +972-8-9468265]
Sulfonylurea herbicides exhibit soil activity at extraordinarily low rates of application (g/ha).
However, even at this low rate, some of these herbicides persist in the soil for more than one season,
and may cause injury to the following crop. Analytical methods, such as GC (gas chromatography)
and HPLC (high performance liquid chromatography), are not sensitive enough for determination of
biologically active residues of sulfonylureas. The aims of this study were to (i) develop a sensitive
bioassay suitable for quantitative estimation of sulfonylurea herbicides in soil and water, and (ii)
evaluate their persistence as affected by soil characteristics. Red beet was the most sensitive species
to triasulfuron and tribenuron-methyl, and sweet corn was the most sensitive to chlorsulfuron and
sulfometuron-methyl. ECs0 (the herbicide concentration that causes 50% inhibition in root length)
for these herbicides was in the range of 0.1 to 0.5 ppb in soil and water.
The sulfonylurea sulfometuron-methyl and imazapyr (an imidazolinone), are widely used in
Israel. The root length bioassay showed that bean, lentil, pea, sunflower and sorghum seedlings are
sensitive to sulfometuron-methyl (1 ppb) and relatively tolerant to imazapyr (10 ppb). Therefore,
they can be used as bioassay plants to identify the applied herbicide.
The study of the sulfonylureas' persistence as affected by soil characteristics showed that
tribenuron-methyl dissipation was the fastest, whereas the dissipation rates of sulfometuron-methyl,
chlorsulfuron and triasulfuron were similar. The rate of chemical hydrolysis of all herbicides was
lower than that of microbial degradation.
A bioassay was conducted to estimate the movement of sulfonylureas in soil. Sulfometuronmethyl movement was greater in loamy sand than in clay loam. Herbicide movement was influenced,
to a large extent, by the irrigation regime. Concentrations higher than 10 ppb in the leachate water
of 20-cm soil columns, indicated the potential of sulfonylureas to leach below the plowing layer.
The developed bioassay is simple, rapid and suitable for detection and quantification of sulfonylurea
residues in soil and water, and can be applied as a tool to study the behavior and fate of sulfonylureas
in different soils.

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C: TOLERANCE TO HERBICIDES AND RESISTANCE TO BROOMRAPE OF CROP PLANTS
Oxidative Stress Response in Beans (Phaseolus vulgaris)
O. Shainberg, 1 B. Rubin, 1 H.D. Rabinowitch 1 and E. Tel-Or z
1Dept. of Field Crops, Vegetables and Genetics [Fax: +972-8-9468265] and 2Dept. of Agricultural
Botany, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel
The effect on the antioxidative enzymes in the cell of exposing bean (Phaseolus vulgaris L.)
plants to two different light intensities for a short period of time was examined. The plants were
grown under a 16-h photoperiod in a phytotron. Twelve days after sowing, the plants were separated
into two different light regimes: some of the plants continued growing under a light intensity of
1300 # E.m-2.sec-1; other plants were shaded to 20% of the light intensity for 48 h. Light
intensities affected the activity of some protective enzymes involved in the antioxidative system.
The main influence was found with cytosolic superoxide dismutase (SODcyt) and glutathione
reductase (GR) activities, which were significantly increased by the high light intensity. Other
enzymes, chloroplastic superoxide dismutase (SODchl) and catalase, were less affected. Protein and
chlorophyll contents were unaffected. Plants with the higher activity of GR and SODcyt showed
increased tolerance to additional oxidative stresses imposed by paraquat and SO2 treatments. We
suggest that those enzymes are responsible for the cross-protection observed in bean leaf from
additional oxidative stresses.

Response of Vetch (V/c/a spp.) Genotypes to Orobanche aegyptiaca
Y. Goldwasser, 1 Y. Kleifeld, 1 D.M. Joel, 1 D. Plakhine 1 and B. Rubin 2
1Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900 [Fax: +972-4-9836936];
and 2Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem,
Faculty of Agriculture, Rehovot 76100, Israel
Most vetch genotypes, which are important forage crops in the Mediterranean region, are
susceptible to the holoparasites Orobanche aegyptiaca and O. crenata. Greenhouse experiments
conducted in pots containing loamy clay soil inoculated with O. aegyptiaca seed, demonstrated that
purple vetch (Vicia atropurpurea) genotypes 'Popany' and 'Sadot' are resistant (R) to the parasite,
whereas common vetch (V. sativa) genotypes 'Yovel' and '473-A' are susceptible (S). When R
genotypes were grown on glass fiber paper in plastic bags, a significantly higher rate of parasite
seed germination and attachments was observed as compared with that on S genotypes. On the S
host roots, O. aegyptiaca attachments developed into tubercles and flowering stems, whereas on the
R host roots no further development of the parasite was observed. The resistance of purple vetch
genotypes to O. aegyptiaca was sustained at different temperature regimes (day/night 17/12, 22/17
and 27/22~
Microscope studies revealed that on the R vetch genotypes' roots, necrotic lesions
were developed, surrounding the contact points of the parasites, radicle. Further development of
the parasite ceased either in the root cortex or when reaching the vascular cylinder. A reddishbrown secretion was detected at the host-parasite interface, filling the apoplastic spaces including
the cavities of R host vessel elements. These findings suggest involvement of defense mechanism(s)
induced by parasite attachment.

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D: PARASITIC WEEDS

Orobanche Species Identification Using Molecular Markers

D.M. Joel, V. Portnoy, G. Tzuri and N. Katzir
Dept. of Weed Science, ARO, Newe Ya 'ar Research Center, Haifa 31900, Israel
[Fax: +972-4-9836936]
Five Orobanche (broomrape) species are known as serious weeds in Israel. The distinction
between the species is highly relevant, because they attack different crops.
DNA markers were raised for the identification of each of the important Orobanche species,
using a random amplified polymorphic DNA (RAPD) technique that is based on the use of short
primers of arbitrary nucleotide sequence in the polymerase chain reaction (PCR). This method has
been shown to be useful for a wide range of applications including DNA fingerprinting, and for the
estimation of genetic relationships within and between species. In contrast to the isozyme markers,
DNA-based markers are not dependent on environmental and developmental factors and have been
applied successfully to discriminate between individual genotypes.
In order to confirm the interpretation of RAPD bands, Southern hybridization patterns of
RAPD products of the various species were used. Hybridization is very important especially in
species diagnostics, because parallel RAPD bands of a specific primer are similar only in molecular
size, whereas parallel hybridization bands are similar also in molecular sequence. The diagnostic
information obtained from RAPD products is valuable for the study of Orobanche in agricultural
areas. Probes are now available for most relevant species.
Using RAPD primers we were able to confirm the separation of species belonging to section
Trionychon from species belonging to section Osproleon and to distinguish clearly O. cernua Loefl.
from O. cumana Wallr., and O. aegyptiaca Pets. from O. ramosa L. The validity of the molecular
markers found for O. cumana and O. crenata was confirmed on plants of the same species that were
collected in Spain and Bulgaria.

Developmental Mechanisms in the Parasitic Plant Orobanche and
Its Relations with the Host
Dalia Losner-Goshen, 1 D.M. Joel 1 and A.M. Mayer 2

1Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900 [Fax: +972-4-9836936];
and 2Dept. of Botany, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Orobanche has two life phases. The first is a short independent phase, the elongation phase,
which begins with germination of the seed. When the radicle reaches a host root, the elongation
phase stops and the second life phase of the parasite, the parasitic phase, starts. The conical root
apex becomes roundish at this stage as a result of cell divisions in the external cell layer. The cells
around the apex become papillate as a result of cell extension at the outer surface. The extended root
apex with its papillae form the attachment organ of Orobanche. At this stage starch, instead of lipids,
accumulates in the apical cells. The papillae have a dense cytoplasm with many mitochondria and
a well developed Golgi apparatus. The outer cell walls of the papillae have a pecto-cellulotic wall
layer covered by an outer cuticular wall. These walls carry small (up to 2 #m) and large (4--6 #m)
external protuberances. A secretory substance that stains for carbohydrates accumulates between the
cell walls and the cuticle that covers them, forming a bubble-like structure. Seedlings and calli of
Orobanche are able to produce and secrete pectinmethylesterase (PME) and polygalactur6nase (PG).
Immunogold staining using antibodies to PME showed that most of the labeling is in cell wails.
Based on the studies of the enzyme involved, on light microscope work and on the ultrastructural
studies using conventional and immunogold staining, we were able to clarify some points regarding
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the penetration mechanisms. The first stage of penetration is facilitated by enzymatic separation
between the epidermal cells. A decrease in immunogold labeling of pectins was found in host cell
walls attached to parasite cells; this seems to be evidence of PME and PG activity. Crushed epidermal
cells and folding of epidermal cell walls near the penetration site provide evidence for mechanical
penetration. The penetration process through the epidermis is probably a combination of enzymatic
and mechanical activities.
In the root cortex and the vascular cylinder, degraded host cell walls were seen beside crushed
host cells, foldings of host cells and changes in wall pectin composition. This is evidence that
additional enzymes are involved in the penetration processes.

Selective Control of Broomrape in Carrots and Vetch with Foliar-Applied
Imidazolinone Herbicides
R. Jacobsohn, Z. Tanaami and H. Eisenberg

Dept. of Vegetable Crops, ARO, The Volcani Center, Bet Dagan 50250, Israel
[Fax: +972-3-9669642]
Various herbicides of the imidazolinone group, foliar-applied, have demonstrated activity against
broomrape (Orobanche spp.) in experiments in carrots (Daucus carota L.) and in vetch (Vicia sativa
L. var. 'Yovel'). The purpose of the experiments in carrots was to replace glyphosate, which is
widely used as a foliar treatment for broomrape control in Umbelliferae crops and has a narrow
margin of safety. Glyphosate can be hazardous to carrots if under stress; the problem is even more
severe in vetch.
The effect of imazethapyr, imazameth and imazamox (AC-299263) (American Cyanamid Co.)
as well as flumetsulam (DE 498) (DowElanco) on selective broomrape control was tested in two
commercial fields of carrots, planted on Oct. 3, 1994 and Nov. 13, 1994, in Kibbutz Sheluhot in
the Bet She'an Valley. The three imidazolinone herbicides as well as two sulfonyl urea herbicides
and flumetsulam were tested for selective broomrape control in vetch, in an experimental field at Bet
Dagan.
Carrots The herbicides belonging to the imidazolinone group controlled almost all the
broomrape plants in carrots of both planting dates, with somewhat greater activity in the first
planting. Three applications of imazameth at a rate of 1.25 g a.i./ha did not provide complete
broomrape control. However, three applications of all other treatments at rates ranging from 1.25
to 5.0 g a.i./ha resulted in excellent broomrape control. Three applications of various combinations
of 20 and 40 g a.i./ha of imazethapyr and imazamox also resulted in nearly complete broomrape
control. Imazamox was slightly less successful in the control of broomrape in the second planting;
metosulam (DE 511) and glyphosate suppressed broomrape emergence but damaged the crop.
Vetch Foliar applications of the imidazolinone herbicides provided good control of both Egyptian
and crenate broomrape in vetch, at rates generally twice as high as in carrots. Three applications
of 1 g a.i. of imazameth and three applications of 20, 40 and 40 g a.i./ha imazethapyr resulted in
complete selective control of the two broomrape species. Glyphosate and flumetsulam gave complete
broomrape control but resulted in crop damage. Metosulam caused heavy damage to the crop.
Cyclosulfamuron damaged the crop and not the broomrape.

Isolation of Mycoherbicidal Pathogens from Juvenile Broomrape Plants
Ziva Amsellem, 1 Y. Kleifeld, 2 Z. Kernyi, s L. Hornok, 3 Y. Goldwasser 2 and J. Gressel 1

1Dept. of Plant Genetics, WeizmannInstitute of Science, Rehovot 76100, Israel
[Fax: +972-8-9344181]; ZDept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900,
Israel; and 3Inst. for Plant Science, Agricultural Biotechnology Center, GOd6110,Hungary
Phytoparasitica 24:3, 1996

207

The parasitic broomrapes (Orobanche spp.) are widely spread weeds, halving yields of ca 4%
of the world's crops. As these plants attach to crop roots, they cannot be controlled mechanically
except by removing their flower stalks after much of the damage to the crop yield has already been
done. They are not usually amenable to selective herbicides (except those applied postemergence),
as most herbicides cannot differentiate between crop and parasite. Biological control could be an
effective answer. The isolation of two highly parasitic fungi, Fusarium arthrosporioides strain
E4a and E oxysporum strain Eld, is reported from diseased, juvenile, emerging Orobanche flower
stalks. Both organisms meet Koch's criteria for being primary pathogens. DNA RAPD fingerprinting
showed that they indeed differ from each other and from many other Fusarium spp. as well as
other formae speciales of E oxysporum. Tomato plant roots dipped into a fungal suspension and
planted in broomrape-infested soil were protected for long periods, There are still many experiments
to be performed before agricultural use can be envisaged. These include studying the host range
of the pathogens on different Orobanche strains and species, soil residue analyses, pathogenicity
on crops cultivated in the same geographical region to determine incompatibilities, as well as the
development of cost-effective application technologies. It is possible that basic studies of the
defenses of broomrape can lead to synergies using chemical synergists to suppress defenses and/or
facilitate the action of microorganisms.

Ethylene and Temperature Affect Induction of Resistance to Orobanche aegyptiaca
Penetration in Helianthus annuus Inbred Line SW 501, in an In Vitro Bioassay
System
Adiva Shomer-Ilan

Dept. of Botany, Tel-Aviv University, Tel Aviv 69978, Israel [Fax: +972-3-6409380]
The angiosperm weed Orobanche (broomrape) is a known root holoparasite causing severe
economic damage in the Mediterranean area. Analyzing natural host resistance mechanisms might
provide a lead to solving the problem. We used sunflower high-temperature-resistant inbred line SW
501, the resistance of which was evaluated by Noemi Ish-Shalom-Gordon et al. (1993). Seedlings
were grown and assayed for resistance to broomrape penetration and inducers of such resistance,
in an in vitro bioassay system of aluminum-foiled-polyethylene bags with 40% Hoagland solution.
The seedlings were exposed to constant conditions (15+0.5 or 24+1~ 12-h photoperiod, 150 #M
photon m -2 s-l). When 2 weeks old, the seedlings were inoculated with germinated O. aegyptiaca
seeds. The percentage of infested plants was recorded for another month.
Sunflower seedlings grown at 15+0.5~ were found to be susceptible to the parasite, 87% of
66 tested seedlings being infested. On the other hand, seedlings grown at 24-1-1~ were found to
be resistant to broomrape; 18% of 46 tested plants were infested (in agreement with Ish-ShalomGordon's findings). To identify inducers of systemic resistance at 15.5+0.5~ 2-week-old seedlings
were exposed for 24 h to salicylic acid or ethylene before inoculation. Only ethylene induced
resistance, with 14% of 44 tested plants being infested. Thus, ethylene and temperatures above 20~
induce resistance. This phenomenon is currently being subjected to molecular analysis.

On the Biology and Selective Control of Field Dodder (Cuscuta campestris)
Ela Nir and B. Rubin

Dept. of Field Crops, Vegetablesand Genetics, The Hebrew Universityof Jerusalem, Faculty of
Agriculture, Rehovot 76100, Israel [Fax: +972-8-9468265]
Field dodder (Cuscuta campestris), a non-specific parasitic weed, causes damage and yield loss
in a wide range of host species worldwide. The parasite seedling coils around the host and penetrates
its tissue and vascular system via haustoria. The dodder exploits the host by withdrawing assimilates,
208

Meetings

nutrients and water, thereby reducing crop quality and yield. Laboratory and field experiments were
conducted to elucidate the effect of edaphic and environmental conditions on dodder germination and
development, as well as its response to herbicides.
Maximum germination occurred at 15~ to 35~ no seed germination was observed below 10~
or above 40~ In a sandy soil (at Rehovot), maximum emergence occurred from the soil surface,
where most of the seeds emerged within 3 days. Sowing in heavier soil and a deeper layer resulted
in reduced and delayed emergence, with no emergence from a depth below 10 cm. The viability of
seeds buried at various soil depths in the field, declined with time.
Soil-incorporated herbicides, known as cell division and development inhibitors (dinitroanilines,
pronamide, thiazopyr and isoxaben), inhibited dodder germination and arrested its vegetative growth
before or soon after attachment to the carrot plant. The hypothesis that dodder employs a strong sink
('super sink'), and hence that phloem-mobile, non-selective herbicides applied on the host will be
withdrawn rapidly by, and accumulate in, the parasite, was examined. Preliminary results indicate
that yields of carrots infested with dodder were higher than those of uninfested plants treated with
certain rates of thiazopyr or imazethapyr. The potential of using low rates of non-selective herbicides
for selective control of field dodder is currently being examined.

E: DIFFERENT APPROACHES TO WEED CONTROL
Inhibiting a Plant Defense Mechanism to Enhance the Biological Control of the
Weed Abutilon theophrasti b y the Fungus CoUetotrichum coccodes
Daphna Michaeli, 1 V. Kampel, 2 A. Warshawsky 2 and J. Gressel 1
1Dept. of Plant Genetics [Fax: +972-8-9344181] and 2Dept. of Organic Chemistry, The Weizmann
Institute of Science, Rehovot 76100, Israel
A specific fungus, Colletotrichum coccodes, can serve as a biological agent for control of the
widespread pernicious weed Abutilon theophrasti. The lowest effective inoculum dose is more
than 107 spores/ml, which is not economical. We are attempting to overcome this problem with
compounds that specifically inhibit the weed's defense mechanism. The synthesis of callose is an
important defense mechanism in various plants infected by Colletotrichum spp. Synergists specially
synthesized for the Abutilon-C. coccodes pathosystem are aimed at preventing callose formation by
inhibiting the enzyme callose synthase, an enzyme requiring calcium as a cofactor. The fungus
has a minuscule calcium requirement, and when inoculum was pregrown in a calcium-containing
medium, it did not lack calcium for growth, despite the inhibitor. Fiftyfold higher concentrations
of inhibitor than the calcium content of the medium had no significant effect on fungus growth.
Initial evidence for a possible synergism between C. coccodes spores in combination with the callose
synthesis inhibitors was found in preliminary greenhouse and laboratory experiments with inoculated
Abutilon plants. The most susceptible organs were cotyledons and young buds. An experimental
system was calibrated using cotyledons from young Abutilon plants floating on water in plates that
were point-inoculated for various incubation periods. Fungal growth on leaves was measured by
ELISA (enzyme-linked immunosorbent assay), applying a specific anti-C, coccodes antibody. In
parallel, Abutilon cotyledons were stained for callose. Small fluorescent spots resulting from callose
synthesis appeared adjacent to inoculation drops 36 and 54 h after inoculation. This system is now
used for quantification of fungal infection and callose formation with and without the inhibitors.
This research was kindly supported by a student scholarship in memory of Lynn Bilik and an
award from the Weed Science Society of Israel.

Phytoparasitica 24:3, 1996

209

Improved Control of Purple Nutsedge (Cyperus rotundus) Using
Plant Growth Regulators
M. Yogev,1 M. Negbi 2 and B. Rubin 1
1Dept. of Field Crops, Vegetables and Genetics [Fax: +972-8-9468265] and 2Dept. of Agricultural
Botany, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel
Purple nutsedge (Cyperus rotundus) is a troublesome weed in many crops, and considered to
be the world's most noxious weed. It propagates by forming tubers dispersed in different soil
depths and shallow basal bulbs which develop into shoots. Traditional weed control methods hardly
achieve any appreciable control of this weed or reduction in the number of tubers in soil. To reduce
herbicide use and yet achieve acceptable control, a series of experiments was carried out in which
purple nutsedge seedlings were treated with mixtures of plant growth regulators (PGR), in order
to modify the seedlings' growth pattern. Spraying gibberellic acid at 10-3M and CPPU (Agan
Chemical Manufacturers, Israel), a cytokinin, 10-4M over sprouting shoots, did not adversely affect
their aboveground development but prevented that of tubers. In field experiments in which the
PGR mixture was applied postemergence twice, the underground shoots (rhizomes) modified their
potentially dia-plagio- and ortho-gravitropic growth response into a negative one, to become aboveground shoots. Under such conditions, virtually no tubers were formed. When PGR treatments
were followed by application of reduced rates of herbicides, the weed control efficacy was increased
synergistically. These promising results open up new possibilities to facilitate the control of this
noxious weed.

New Approaches in the Control of Purple Nutsedge (Cyperus rotundus)
J. Hershenhorn, R. Aly, Y. Lavan, S. Golan, G. Herzlinger and T. Hilf

Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900, Israel
[Fax: +972-4-9836936]
Purple nutsedge (Cyperus rotundus L.) is considered to be one of the world's worst weeds,
especially in the tropical and subtropical regions; it is exceedingly noxious also in Israel. Its rapid
growth, prolific propagation through a complex underground system of rhizomes and tubers, and its
narrow leaves with a thick cuticle, make it extremely refractory to control by mechanical or chemical
means.
The following alternative approaches to control this noxious weed are being investigated: (i) B.
Rubin et al. (Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel) reported
that purple nutsedge plants sprayed with a combination of plant hormones did not produce tubers. We
are investigating the possibility that transformation of the biological control agent Cercospora caricis
pt. rotundus, a pathogen of purple nutsedge, with the genes for IAA and cytokinin production, will
achieve the same results. A transformation system was already established.
(ii) We have recently demonstrated that exposure of C. rotundus tubers to minute quantities
(5-15 #1) of essential oil from lemongrass (Cymbopogon flexuosus), Syrian oregano (Origanum
syriacum) and Micromeria fruticosa completely inhibited germination. Purification of the active
fractions and possible application in the field are under study.
(iii) Under greenhouse conditions, more than 85% of C. rotundus tubers did not germinate in
the presence of Cicer arietinum plants. Root exudates of the 'Hadas' variety showed the greatest
inhibitory effect. Similar results were obtained with concentrated root exudates from the same
variety applied on tubers in petri dishes. Purification of the active compound(s) and tests of possible
application in the field are being conducted.

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Meetings

How was Bermudagrass Controlled before the Era of Herbicides?
M. Horowitz

Dept. of Ornamental Horticulture, ARO, The Volcani Center, Bet Dagan 50250, Israel
[Fax: +972-3-9660589]
The perennial bermudagrass, Cynodon dactylon, is characterized by subterranean rhizomes
capable of rapid growth and regeneration under favorable moisture and temperature conditions.
Due to its large biomass and allelopathic effects, bermudagrass is strongly competitive to cultivated
plants,
Bermudagrass was identified in the 19th Century as a common weed by botanists touring
the region. The intensification of local agriculture and the introduction of modem techniques of
irrigation and tillage, from 1900 onwards, strongly increased the infestation by bermudagrass, which
eventually became the most noxious weed in irrigated land.
Since there was no other effective control method at the time, 'bahar' - manual removal of weeds
from the soil - was the technique recommended in preparation of new plantations. A ditch was dug
as deep as rhizomes penetrated - down to 50 cm and more in sandy soil - and all pieces of rootstock
were individually pulled out. The labor was hard and slow; under optimal conditions, a worker would
clean 40 m 2 per day. The method remained in use until the 1930s, mainly for export crops such as
citrus, and was gradually replaced by mechanical cultivation.
Trials with deep soil tillage showed that cutting the subterranean system often increased
infestation, since dormant sections sliced off the rhizome sprouted and generated new plants.
However, repeated cultivation which suppressed the foliage, led to depleted plant reserves and
gradually killed the weed. This method was introduced in the late 1920s for field crops and citrus
plantations. Successful control of established bermudagrass was reported after 10--12 cultivations at
1-2 week intervals; however, irregular timing of the cultivation resulted in renewed infestation.
In the 1940s, herbicidal oils were tested for control of bermudagrass. Dalapon and mixtures
of amitrole and simazine were introduced in the late 1950s, and bromacil, selective to citrus, was
registered in 1966.

Effect of Drift-Retarding Chemicals
M. Cohen, 1 I. Hirsch 2 and A. Veneziani 3
1Weed Control Co. Ltd., Bet Dagan 50250 [Fax: +972-3-9663020]; 2Chem-Nir Ltd., Kefar
Shemaryahu 46910; and 3Tiveon-Chem Co., Haifa 31333, Israel
Spray drift is an unavoidable accompaniment to all spraying activities, but can be reduced and
regulated by appropriate, drift-retarding materials. During 1995 several trials were carried out to
determine the degree of efficacy of such materials. Drop Zone DC* (Helena Chemical Co., Memphis,
TN, USA) at 50 ml/100 l; Nalcotrol* (Nalco Chemical Co., Naperville, IL, USA) at 40 ml/100 l; and
A-41* (San Ag, Los Angeles, CA, USA) at 30 ml/100 1of total volume were sprayed by helicopter at
50 l/ha. The number of droplets per square inch on marked targets was counted. Drop Zone DC* was
also applied from the ground, by a motorized backpack sprayer, at 50 and 75 g/l of spray solution,
to 30x40-cm white paper target sheets; and at 0, 0.025%, 0.05% and 0.075% of a spray solution,
containing 1675 g a.i./ha of 2,4-D, to young cotton seedlings. Under the test conditions, all trials
throughout indicated a good drift-retarding effect by the three products tested.

*Proprietary name; common names or chemical formulae not applicable.

Phytoparasitica 24:3, 1996

211

By title only
Germination of Orobanche seeds: Scome aspects of metabolism during preconditioning A.M. Mayer and Nurit Bar Nun
Witchweed (Striga spp.), a root parasite of cereals and legumes D.M. Joel

212

MEETINGS

ABSTRACTS OF PAPERS PRESENTED AT

THE INTERNATIONAL CONFERENCE ON
CONTROLLED ATMOSPHERE AND FUMIGATION (CAF)
IN STORED PRODUCTS
April 21-26, 1996
Cyprus International Conference Centre, Nicosia, Cyprus

Institutions assisting in organizing the Conference:
Cyprus Grain Commission, Nicosia, Cyprus
Agricultural Research Organization, Bet Dagan, Israel

A: BIOLOGICAL RESPONSES OF ARTHROPODS TO CA AND~OR FUMIGATION,
AND FOOD OFFERED
Effect of Modified Atmospheres on the Juvenile Stages of Six Grain Beetles
S.T. Conyers and C.H. Bell
Central Science Laboratory, Ministry of Agriculture, Fisheries and Food, Slough,
Berks. SL3 7HJ, UK [Fax: +44-1753-824058]
Adult emergence after exposure of the juvenile stages of six species of grain beetle, Cryptolestes
ferrugineus (Stephens), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (E), Sitophilus
granarius (L.), S. oryzae (L.) and Tribolium castaneum (Herbst), to three modified atmosphere (MA)
mixtures, was assessed at 15~ and 70% r.h. The use of this low temperature was important as it is
representative of the conditions prevailing in grain stores at the start of the U.K. storage season.
The juvenile stages were exposed to three separate MAs, based on nitrogen, simulated burner gas
and carbon dioxide, with 0.5% or 2% oxygen. The internal grain feeders, R. dominica, S. granarius
and S. oryzae, were able to emerge even after lengthy exposures to the MAs and of these three
species, S. granarius was the most tolerant. Of the other species, T. castaneum was the most tolerant,
its pupae requiring 10 days of exposure to prevent emergence. Carbon dioxide was the most effective
of the MAs, followed by simulated burner gas and then nitrogen. (L)*

Control of the Dermestid Beetle Dermestes maculatus with Controlled Atmospheres
Ana C. S~i-Fischer, C.S. Adler and Ch. Reichmuth
Federal Biological Research Centrefor Agriculture and Forestry, Inst. for Stored Product
Protection, D-14195 Berlin, Germany [Fax: +49-30-8304284]
The leather or hide beetle, Dermestes maculatus De Beer, is one of the most important pests on
dried products of animal origin as well as on leather, furs and other materials. Museums fear the
*L = lecture sessions;P = poster (market place) sessions.

Phytoparasitica 24:3, 1996

213

potential of this pest to destroy insect collections, mummies and other valuable goods. Also the long
larval hairs break off easily and can have severe allergic effects.
Various hypoxic controlled atmospheres were tested under laboratory conditions against all
stages of D. maculatus at 25 ~ and 30~
r.h. Using an atmosphere of pure nitrogen or pure
carbon dioxide, respectively, complete control of all stages could be achieved within 48 h. The same
effect w