Evidence that DL-3-aminobutyric acid and acibenzolar-S-methyl induce resistance against bacterial head rot disease of broccoli

Head rot of broccoli caused by Pseudomonas marginalis (Brown) Stevens and P. fluorescens Migula is a major disease in Brittany (France). To date, no accession with a satisfactory field resistance has been identified, and available pesticides are not effective in controlling the disease. The aim of this study was to test whether acibenzolar-S-methyl (ASM), DL-3-aminobutyric acid (BABA) and potassium phosphonate (K(2)HPO(3)), known to induce resistance against various diseases, can help protect broccoli against head rot. The susceptible broccoli F1 hybrids Marathon and Shogun were grown in a greenhouse until head formation. They were then sprayed with ASM (0.23 mM AI), BABA (20 mM AI) or potassium phosphonate (37.41 mM AI) until runoff. In one experiment, heads from treated plants were excised, inoculated (10(4) cfu ml(-1)) and incubated in Magenta GA7 vessels. In another experiment, heads were inoculated on treated living plants. Disease ratings were made 5 days after inoculation. Antibiotic- and water-treated plants served as controls. Results obtained showed that, on excised treated heads, potassium phosphonate was not protective and disease scores were comparable with those of the water control. BABA- and ASM-treated excised heads were poorly, but significantly, protected. On whole plants with heads attached, the latter two compounds were much more effective. ASM-induced resistance increased in effectiveness over 8 days after inoculation, whilst that induced by BABA decreased. This result suggests that testing disease resistance inducers on excised broccoli heads is not accurate. ASM and BABA may offer alternative methods for controlling head rot of broccoli.     

Efficacy and residues of phloxine B and uranine for the suppression of Mediterranean fruit fly in coffee fields

The field efficacy of a bait containing phloxine B, uranine and Provesta 621 protein was tested against Mediterranean fruit fly (Ceratitis capitata; Medfly) by aerial and ground spraying in about 84 ha of coffee fields in Kauai, Hawaii, USA. Concurrently, soil and crop samples were collected from the aerially sprayed field and its unsprayed control field for residue studies. Efficacy of the sprays was assessed through trapping with both protein-baited and trimedlure-baited traps and through the infestation level of coffee cherries collected at least three-quarters ripe. The C capitata population was low at the start of the aerial and ground spray studies, but dramatically increased in the control fields. This increase coincided with initial ripening of coffee cherries. During times of peak population levels, C capitata populations were reduced by more than 91% in the ground-sprayed field and 99% in the aerial-sprayed field, relative to the populations in their respective control fields and based on protein-baited trap catches. Results of residue analyses indicated that uranine dissipated quickly compared with phloxine B on coffee and soil. Coffee samples collected at pre-spray periods had phloxine B residues of 7.2-25.5 ng g-1 on berries. Phloxine B concentrations were much higher on coffee leaves (163-1120 ng g-1). Lower concentrations of the dye were found from coffee samples collected during rainy days. Average phloxine B concentrations immediately after spraying were 56 and 2840 ng g-1 in coffee berries and leaves, respectively. Dissipation of phloxine B on berries was fast, with a half-life (t1/2) of 3 days. Dissipation of phloxine B on leaves was fitted to two linear phases: the initial (0-4 days) with a shorter t1/2 of 3 days and the later phase (4-28 days) with a longer t1/2 of 15 days. Average concentrations of phloxine B in the top soil ranged from 50 to 590 ng g-1 at pre-spray. Phloxine B initial concentration (770 ng g-1) reached a plateau immediately after the last spraying, but showed a steady decline over time with t1/2 of 16 days. Fast dissipation of the dyes in the field indicates that these chemicals may be environmentally compatible and therefore a promising alternative for fruit fly control.     

沼液对韭菜迟眼蕈蚊的防治效果

通过室内选择性测定和田间试验,评价了沼液对韭菜迟眼蕈蚊的防治效果。结果表明,沼液对韭菜迟眼蕈蚊表现出一定的驱避活性,对幼虫的驱避率、拒食率分别达55.30%、53.81%,雌雄成虫选择反应率分别为33.2%、30.5%,对雌虫产卵驱避率为36.82%。田间试验结果表明,以沼液∶水(1∶1)处理幼虫、成虫,随着时间的延长防效逐渐提高,处理后45d防效达到最大,分别为43.16%、56.50%。     

苍耳不同分离物对害虫的拒食和忌避活性

为跟踪分离苍耳的活性成分,对苍耳叶和果实的甲醇提取物进行了液-液萃取分离,测试各萃取分离物对小菜蛾(Plutella xylostella)、菜青虫(Pieris rapae)和桃蚜(Myzus persicae)的拒食、忌避(或产卵忌避)活性以及对其化蛹和羽化的影响。结果显示,苍耳的乙酸乙酯分离物较之于甲醇水分离物具有更高的活性。在0.05 g/mL处理浓度下,苍耳叶乙酸乙酯分离物对菜青虫和小菜蛾幼虫选择性拒食率高达100%和44.13%,对菜青虫非选择性拒食率为94%,对小菜蛾的选择性产卵忌避率都在50%以上,对桃蚜的选择性忌避率高于70%;同时,苍耳果实乙酸乙酯分离物处理叶片后,菜青虫幼虫无一化蛹,小菜蛾高龄幼虫发育为成虫的比率仅为对照的13.80%。以上结果提示,苍耳的有效活性成分主要存在于乙酸乙酯分离相中,对菜青虫的作用效果好于小菜蛾。     

西兰花植株残体还田对棉花黄萎病的防治效果及其安全性评价

本研究探讨了温室和田间试验条件下西兰花植株残体还田对棉花黄萎病的防治效果以及西兰花残体对棉花生长的安全性，以期为深入研究西兰花植株残体对棉花黄萎病的生态防治机制提供依据。将粉碎的西兰花植株残体与培养基质分别按1%、3%、5%、7%和14%处理混匀，在（28±2）℃条件下分别腐解7和30 d后种植棉花，测定其对棉花出苗率、株高的影响以及对黄萎病的防治效果。研究结果表明，当腐解时间为7 d，西兰花残体处理比例为1%和3%时，棉花出苗率与不添加西兰花残体的空白对照处理不存在显著差异，但对株高具有显著促生长作用，增幅分别为19.46%、42.41%和36.96%；西兰花残体添加比例为5%、7%和14%时，对出苗具有不同程度的抑制作用。当腐解时间为30 d时，上述各比例西兰花残体处理后的棉花出苗率和株高与空白对照之间差异不显著。西兰花残体处理显著降低了棉花黄萎病的发病率和病情指数，其21 d后的防治效果达到72.55%。田间试验表明，西兰花残体在棉花全生育期内对黄萎病的防治效果为43.06%。综合分析表明，西兰花残体的施入，促进了棉花生长，降低了黄萎病的发病率和病情指数，且在发病初期的防治效果优于后期。研究结果为深入研究西兰花残体防治棉花黄萎病的生态机制提供理论依据和技术指导，最终为棉花黄萎病的绿色防控和化学农药的减量提供了新途径和思路。     

A three‐year field study on the short‐term effects of insecticides used to control cereal aphids on plant‐dwelling aphid predators in winter wheat

Short‐term effects of six insecticides used to control aphids were assessed in wheat on plant‐dwelling aphid predators. Products were applied to small plots of winter wheat in June or at the beginning of July and the densities of predators were estimated three days after treatment using a beating method. Insecticides were tested in 1994, 1995 and 1997 at a single dose, corresponding to their maximum recommended field rate in Belgium. Fluvalinate and esfenvalerate did not significantly reduce catches of syrphid larvae compared to the control but ladybirds were affected by these compounds. Pirimicarb was the only product tested that had no effect on ladybirds. However, syrphid larvae appeared sensitive to this product. Cyfluthrin, deltamethrin and phosalone reduced catches of both syrphids and ladybirds. Populations of lacewing larvae were unaffected by any of the insecticide treatments. Syrphid larvae were the most abundant aphid predator and Episyrphus balteatus the most common species. Ladybirds (Coccinella septempunctata and Propylea quatuordecimpunctata) were less numerous and only a few Chrysoperla carnea larvae were recorded. These results indicate that products that are less toxic to syrphid larvae, like esfenvalerate and fluvalinate, may be preferable to other compounds to control cereal aphids in wheat in spring and early summer. However, other criteria, such as the effectiveness of the different aphid‐specific predators, cost, efficacy of the treatment and side effects on other aphid antagonists (including parasitic hymenoptera and polyphagous predators) must also be taken into consideration. © 2000 Society of Chemical Industry     

油酸甲酯溶剂对高效氯氟氰菊酯水乳剂物理性状及药效的影响

采用浸渍法、表面张力仪测定法和液滴干燥法分别测定了不同油酸甲酯含量的药液在3种作物叶片上的最大稳定持留量、表面张力及干燥时间,以浸叶法与浸虫法测定了不同油酸甲酯用量下高效氯氟氰菊酯对菜青虫及小地老虎的室内毒力,并进行了田间药效试验。结果表明,在2.5%高效氯氟氰菊酯水乳剂中油酸甲酯用量从5%提高至35%,稀释药液最大稳定持留量提高21.08%~125.14%,表面张力降低6~12 mN/m,干燥时间延长6~20 min,且高效氯氟氰菊酯对菜青虫和小地老虎的毒力明显增强;田间增加油酸甲酯用量可明显提高高效氯氟氰菊酯对菜青虫的防治效果,3 000倍液药后7天防效从79.22%增至96.54%。     

粉质拟青霉侵染菜青虫致病过程的研究

应用电镜扫描技术观察了粉质拟青霉 990 5菌株对菜青虫的侵染过程 ,根据感病虫体外部症状进行病情分级 ,并应用石蜡切片法观察了不同感病程度菜青虫虫体内部的组织病变情况。结果表明粉质拟青霉菌丝侵入菜青虫血腔后首先侵入脂肪体细胞 ,并证实脂肪体是粉质拟青霉繁殖最多的部位。致死状态表现为 :1级 ,感病菜青虫只是体壁出现病变 ,2级 ,菜青虫已死亡 ,体内各组织均发生不同程度的病变。 3级 ,菜青虫体内几乎所有的组织器官都已解体。     

Chlorpyrifos residue levels in avian food items following applications of a commercial EC formulation to alfalfa and citrus

Two 10-day field residue studies were conducted to measure the amount of chlorpyrifos residue found in typical avian food following applications of a commercial 480 g liter(-1) EC (Lorsban 4E) at 1.1 kg AI ha(-1) (1 lb AI acre(-1)) to alfalfa and at 2.3 kg Al ha(-1) (2.0 lb AI acre(-1)) to citrus. Avian food items used in these studies included: crickets (Acheta domestica (L)), earthworms (Lumbricus terrestris L), darkling ground beetle larvae (Tenebrio molitor L), seed heads (Triticum sp), and naturally occurring flying and ground-dwelling insects. The studies incorporated a design involving three main study plots placed within larger treated areas of an alfalfa crop and a mature orange grove. The three main study plots represented three replications and each contained four sub-plots. One sub-plot, on each study plot, was sampled on day 0 (2-h post-application), day 1, day 5 and day 10 post-application. Chlorpyrifos residues were present in all avian food sampled following the application; however, residue levels were lower than estimated residue values typically used by the US EPA to establish expected environmental concentration (EEC) used in screening assessments of risk to terrestrial wildlife.     

冀鲁豫和新疆棉铃虫的抗药性

首次系统报道了苦槛蓝对菜青虫的拒食,毒杀作用和影响生长发育的作用。试验表明,１％苦槛蓝氯仿萃取物对菜粉蝶４龄,５龄幼虫的非选择性拒食率均在９４％以上,对４龄幼虫的ＡＦＣ５０,ＡＦＣ９５分别为０．１２％和０．７８％;处理后７２ｈ,４龄试虫的校正死亡率为８０．８％;处理后４ｄ,试虫的平均体重仅为对照的３６．７４％;经１％氯仿萃取物处理,４龄试虫羽化率仅为３．３３％,发育抑制率达８８．８９％。     

Crop rotation effects on Cyperus rotundus and C. esculentus population dynamics in southern California vegetable production

Control options for Cyperus rotundus and Cyperus esculentus (purple and yellow nutsedge) were evaluated within three cropping systems in the low desert of southern California: (1) standard vegetable crop rotation (weed‐free, uncontrolled nutsedge and cultivation) with spring cantaloupe (Cucumis melo) – summer fallow – winter broccoli (Brassica oleracea), (2) cover crop rotation (halosulfuron and smother crop) with spring wheat (Triticum aestivum)/corn (Zea mays) – summer sudangrass (Sorghum sudanense) – Winter Fallow, (3) rotation with solarization (non‐solarization and solarization) with spring wheat – summer fallow/solarization – winter broccoli. After two growing seasons, broccoli was planted without Cyperus control, to study the effect on yield. Cyperus rotundus tubers increased from 0.66 tubers per m² to 1260 tubers per m² in the uncontrolled treatment over two seasons. Cultivation during the growing season reduced C. rotundus tubers by 93% compared with the uncontrolled plots. Cover crop rotation did not reduce the number of C. rotundus tubers significantly, despite the dense sudangrass canopy shading the soil during most of the summer. Cyperus rotundus was effectively controlled by the solarization treatment. All methods controlled C. esculentus, especially when there were no crops growing in the summer. When broccoli was grown after two years of various management strategies, the cultivation treatment showed a 44% yield reduction compared with the weed‐free control, while the solarization treatment increased broccoli yield by 64% compared with the non‐solarization treatment. Rotations that included sudangrass had low broccoli yield when either C. rotundus or C. esculentus were present.     

Evaluation of Bacterial Antagonists for Biological Control of Broccoli Head Rot Caused by Pseudomonas fluorescens

ABSTRACT Pectolytic strains of Pseudomonas fluorescens are opportunistic pathogens of broccoli, causing head rot in temperate regions of the world. In this study, we investigated the potential of two bacterial isolates, P. fluorescens m6418 and Bacillus sp. A24, for biological control of broccoli head rot caused by P. fluorescens 5064, isolated from diseased broccoli in Scotland, UK. P. fluorescens m6418, a Tn5 mutant of wild-type 5064, is nonpathogenic and overproduces an extracellular metabolite with strong antimicrobial activity. In this study, we identified the anti-microbial metabolite produced by strain m6418 as pyrrolnitrin. P. fluorescens m6418 had significant inhibitory effects against strain 5064 both in culture and on broccoli leaves. In an excised broccoli head pathogenicity test, strain m6418, when coinoculated with P. fluorescens 5064, reduced disease by 41%. Bacillus sp. A24 produces an enzyme that can degrade N-acyl homoserine lactones, signaling molecules employed by bacteria for quorum sensing. Bacillus sp. A24 was capable of out-competing P. fluorescens 5064 when grown together in culture, and could degrade the quorum sensing signal of P. fluorescens 5064 (and thereby attenuate its virulence gene production). However, Bacillus sp. A24 had only a limited biocontrol effect on P. fluorescens 5064 in the excised broccoli head assay.     

Aggressiveness ofAlternaria brassicicola to Broccoli

The aggressiveness of 27 isolates ofAlternaria brassicicola to broccoli plants was investigated in a growth chamber environment. Of the 27 isolates 14 were collected from leaves of broccoli plants which had lesions only on leaves, and 13 were collected from plants on which lesions were restricted to stems and/or flowers. There was no significant difference between aggressiveness of isolates collected from leaves and those collected from stems/flowers. However, isolates originating from leaves were more aggressive on leaves than those collected from stems/flowers. No clear evidence could be found to support the hypothesis that there is tissue specification among isolates collected from different plant parts. Generally, disease index was highest on the leaf blade and lowest on the stem.     

Effect of certainBrassica plants on biology of the cabbage aphidBrevicoryne brassicae under laboratory conditions

The development time, mortality, survivorship and reproduction of the cabbage aphidBrevicoryne brassicae (L.) were evaluated on detached leaves of sixBrassica species (cabbage cv. ‘Yalova 1’, cauliflower cv. ‘Early Snowball’, broccoli cv. ‘Marathon’, turnip cv. ‘Antep’, rapeseed cv. local variety, and wild mustard) at a constant temperature of 20°C. Total development time ofB. brassicae was the shortest (8.9 days) on cauliflower and the longest (10.4 days) on cabbage. Mortality of immature stages varied from 16% on cabbage to 88% on turnip. Longevity of the cabbage aphid was the shortest (6.2 days) on mustard, and the longest (21.8 days) on cauliflower. The net reproductive rate was highest (35.98) on cauliflower, and lowest (1.89) on turnip. The intrinsic rate of increase was 0.2345 on cauliflower, followed by 0.2009 on cabbage, 0.1976 on broccoli, 0.1662 on mustard, 0.1357 on rapeseed, and 0.0465 on turnip. Cabbage, cauliflower and broccoli were susceptible host plants for the cabbage aphid. Rapeseed, turnip and mustard showed resistance to the pest.     

Dissipation of three organochlorine and four pyrethroid pesticides sprayed in a greenhouse environment during hydroponic cultivation of gerbera

A wide range of pesticides (insecticides, acaricides and fungicides) is used in the hydroponic cultivation of gerbera. The fate and behaviour of some of these commonly used pesticides (organochlorine and pyrethroid insecticides/acaricides) in a greenhouse installation was investigated. The concentrations of endosulfan, dicofol, tetradifon, permethrin, bifenthrin, cypermethrin and deltamethrin in the air of the greenhouse were related to their physicochemical properties and respective application rates. Of these compounds, endosulfan exhibited the highest concentration in the greenhouse air 2 h after application (10 microg m(-3)), due to its highest volatility; afterwards, up to 12 h post-application, a rapid decrease was recorded which finally led to a concentration of 0.41 microg m(-3) at 6 days post-application. Dicofol exhibited the same trend of dissipation in the greenhouse air; its concentration decreased from 0.27 microg m(-3) immediately after the application to 0.12 microg m(-3) at 6 days post-application. Tetradifon, bifenthrin and permethrin were found at concentrations lower than 0.1 microg m(-3) at 2 h post-application, and cypermethrin and deltamethrin could not be detected. The concentrations of all the above pesticides in the drain water of the open hydroponic system were relatively high immediately after application and decreased rapidly during the following 3 days. In the closed hydroponic system, all the pesticides accumulated in the nutrient solution during the first 24 h after application and slowly decreased in concentration over the following 3 days. The spray operators applying these pesticides were exposed to rather high concentrations and the spray deposits were monitored on the chest and forehead of the operator. Endosulfan exhibited the highest concentrations of the seven pesticides. The organochlorine pesticides (endosulfan, dicofol and tetradifon) were usually detected at higher concentrations on the chest than on the forehead of the operator; pyrethroids were detected at higher concentrations on the forehead than on the chest of the operator.     

虫螨腈与Bt混配对小菜蛾的田间防效及虫螨腈在西兰花上的残留消解动态

研究明确虫螨腈与苏云金芽孢杆菌 (Bacillus thuringiensis, Bt) 混配使用对小菜蛾的田间防效和虫螨腈在西兰花上的残留消解动态，可以为在西兰花害虫防治中减少虫螨腈的用量提供依据。采用手动喷雾法进行了虫螨腈防治小菜蛾的田间药效试验，采用高效液相色谱-串联质谱法 (HPLC-MS/MS) 测定了西兰花上虫螨腈的残留消解动态。结果显示，10%虫螨腈悬浮剂与32 000 IU/mg Bt可湿性粉剂分别按50%推荐剂量混配施用，施药后1、3和7 d对小菜蛾的防效分别为58.11%、65.21%和58.80%，与推荐剂量虫螨腈单剂的防效没有显著差异，但均显著超过了50%推荐剂量虫螨腈单剂及50%推荐剂量Bt单剂的防效，施药后3 d也显著超过了推荐剂量Bt单剂的防效。此外，10%虫螨腈悬浮剂与32 000 IU/mg Bt可湿性粉剂分别按50%推荐剂量混配施用后，虫螨腈在西兰花上的残留消解动态，与施用50%推荐剂量虫螨腈单剂后的残留消解动态接近，但虫螨腈在西兰花中的残留量均显著低于施用推荐剂量虫螨腈单剂的残留量。10%虫螨腈悬浮剂与32 000 IU/mg Bt可湿性粉剂分别按50%推荐剂量混配施用后，虫螨腈在西兰花上的残留消解动态符合准一级反应动力学或一级反应动力学方程，消解半衰期为4.2 d，施药后7 d的残留量为0.072 mg/kg，低于虫螨腈在西兰花的最大残留限量 (MRL) 0.50 mg/kg (参考澳大利亚的MRL标准)，施药后14 d低于定量限 (0.050 mg/kg)。研究结果表明，10%虫螨腈悬浮剂与32 000 IU/mg Bt可湿性粉剂分别按50%推荐剂量混配使用，可以达到减药防治小菜蛾的同时降低虫螨腈在西兰花上残留的目的。     

新化合物氟氧虫酰胺对蔬菜鳞翅目害虫的毒力及田间防治效果

为明确新化合物氟氧虫酰胺(ZJ3757)的杀虫活性,采用浸叶法测定了其对小菜蛾Plutella xylostella、斜纹夜蛾Prodenia litura和甜菜夜蛾Spodoptera exigua的毒力,得其LC50值分别为0.088、0.905和0.095 mg/L,与氯虫苯甲酰胺和氟虫双酰胺的杀虫毒力相当。田间试验结果表明,20%氟氧虫酰胺悬浮剂(SC)在有效成分15 g/hm2剂量下对小菜蛾、甜菜夜蛾、斜纹夜蛾和菜青虫Pieris rapae药后7 d的防效分别达88.41%、92.72%、82.07%和98.39%,与氯虫苯甲酰胺相当,高于或相当于氟虫双酰胺、茚虫威和甲氨基阿维菌素的防效。可考虑将氟氧虫酰胺用于蔬菜上小菜蛾、斜纹夜蛾、甜菜夜蛾和菜青虫的防治。     

寄生小菜蛾的赤眼蜂蜂种选择Ⅲ.三种赤眼蜂对十字花科蔬菜非目标害虫的寄生能力

通过拟澳洲赤眼蜂、短管赤眼锋和碧岭赤眼蜂对菜粉蝶、斜纹夜蛾和甜菜夜蛾卵的功能反应试验，测定了3种赤眼锋对十字花科蔬菜非目标害虫的寄生能力。结果表明，在菜粉蝶卵上，短管赤眼蜂和拟澳洲赤眼蜂都能产卵寄生，短管赤眼蜂的寄生能力远大于拟澳洲赤眼锋，但两者都不能发育成功和正常羽化；在甜菜夜蛾卵上，3种赤眼峰都有较强的产卵寄生能力，且寄生能力差异不大，但碧岭赤眼蜂却不能发育成功和正常羽化；这3种赤眼蜂都能在斜纹夜蛾卵上发育成功并繁殖出下一代，以短管赤眼锋对斜纹夜蛾卵的适应性最强。     

Species and Mating-Type Distribution of Tapesia yallundae and T. acuformis and Occurrence of Apothecia in the U.S. Pacific Northwest

ABSTRACT Eyespot of wheat is caused by the discomycete fungi Tapesia yallundae and T. acuformis. T. yallundae is considered the most important causal agent of the disease in this region but no apothecia of either species have been found in the U.S. Pacific Northwest (PNW). Two compatible isolates of T. yallundae from the PNW were used to inoculate a field plot in the fall of 1998 and apothecia developed in the spring and fall of 2000 on standing wheat stubble. In the spring of 2000, wheat stubble from eight naturally infected fields was examined for the presence of apothecia of T. yallundae and T. acuformis. Apothecia of T. acuformis were found in two fields but no apothecia of T. yallundae were found. This is the first report of apothecia of the eyespot pathogens occurring in the PNW. Species and mating-type distribution of T. yallundae and T. acuformis in the PNW were determined from 817 isolates collected from diseased wheat over 3 years at spatial scales ranging from within fields to across states. In all, 460 isolates were identified as T. yallundae and 357 isolates were identified as T. acuformis with MAT1-1/MAT1-2 ratios not significantly different from 1:1 based on chi(2) tests at most scales tested. The apparent increase in frequency of T. acuformis from previous surveys may indicate a shift in the predominant species causing eyespot. The occurrence of apothecia under field conditions, along with the widespread distribution of mating types of both species, suggests that sexual reproduction may be occurring in both species.     

Basal glume rot (Pseudomonas syringae pv. atrofaciens) on wheat and barley in FRG and resistance screening of wheat1

A survey in 1987 and 1988 revealed that basal glume rot, caused by Pseudomonas syringae pv. atrofaciens, occurred nearly everywhere in FRG. The symptoms of the disease usually consisted of water-soaked dark green to brown lesions on unripe wheat heads, mainly at the basal end of the glumes, which later became dark brown. Forty-six isolates of P.s. atrofaciens were obtained from glumes, seeds and leaves of wheat and barley. For a fast identification of the isolated bacteria, a bio-assay was developed. Four to five-day-old wheat seedlings, grown on wet filter paper in Petri dishes, were pricked at two-three sites with a dissecting needle contaminated with bacteria. After 2–3 days, pathogenic isolates induced brown to black spots. The bacterial isolates from wheat inhibited the growth of several fungi grown on potato dextrose agar. In contrast, an authentic isolate of P.s. syringae obtained from wheat showed no inhibitory effect. During screening for resistance, several cultivars of spring and winter wheat were tested in the greenhouse and/or field tests. The results revealed marked differences in the susceptibility of different cultivars.