Fate of a water-soluble herbicide spray on foliage. Part Ii. Absorption and dissipation of foliar msma deposits: Mathematical modelling

MSMA (monosodium methylarsonate) was applied to rice (Oryza sativa L. cv. ‘Labelle’) plants at weekly intervals from the time the plants were 46 cm high until heading. Each application was to a different set of plants. The sprayed plant tops were analysed for MSMA immediately after spraying and at weekly intervals thereafter until heading. MSMA deposits became completely absorbed after one week and then the total residues declined exponentially to background levels with a half-life of about 15 days. Plant stunting effects depended on the amount of MSMA applied and the rate of growth at the time of application. Sterilisation effects depended on the amount of MSMA applied and the proximity in time of the application to panicle initiation. A mathematical model of the data showed that sterility symptoms were consistent with calculated MSMA concentration in tissue at the time of panicle initiation.     

Foliar residues of aminocarb at tree canopy and ground levels in an experimental spray operation in conifer forests

Foliar residues of aminocarb were measured at tree canopy and ground levels in conifer forests in New Brunswick, Canada, following aerial application of three spray mixtures of aminocarb, one water-based, one in a volatile oil of low viscosity, and the third in a non-volatile oil of high viscosity. For a given volume rate of application, all three mixtures provided similar foliar residues at tree canopy level, but the aqueous and the volatile-oil based sprays provided significantly lower residues on cut foliage positioned at ground level, than the non-volatile oil spray mixture.     

喷雾参数对自走式喷杆喷雾机稻田喷雾农药利用率及雾滴沉积分布的影响

比较在不同喷雾压力和施药液量条件下,采用自走式喷杆喷雾机在水稻分蘖期、孕穗期、扬花期进行喷雾处理的农药利用率、沉积分布均匀性及水稻茎基部雾滴密度的差异,为建立自走式喷杆喷雾机在稻田的高效施药技术提供理论依据。以生物染料丽春红-G作为农药示踪剂,估测不同喷雾参数的农药利用率,并用变异系数、绝对份额比例值比较农药分布的均匀性。同时通过水敏纸收集水稻基部雾滴密度,分析不同喷雾参数下农药雾滴穿透水稻冠层的能力。结果表明:在水稻分蘖期,采用自走式喷杆喷雾机在喷雾压力为1.2 MPa、施药液量为375 L/hm^2条件下喷雾,每个采样点的丽春红-G的平均沉积量仅为0.11 mg,与喷雾压力为0.4 MPa、施药液量为300 L/hm^2条件下喷雾的沉积量相比减少了56.00%。在水稻孕穗期,当喷雾压力为1.2 MPa、施药液量为375 L/hm^2时进行喷雾处理,每个采样点的丽春红-G的平均沉积量达0.26 mg,显著高于其他4个处理。在水稻扬花期,不同喷雾参数间的沉积量差距减小。在合适的喷雾压力和施药液量时,自走式喷杆喷雾机在水稻分蘖期、孕穗期和扬花期进行喷雾处理,农药利用率分别达到40.57%、54.97%和55.50%。综合变异系数和绝对份额比例两个指标,采用自走式喷杆喷雾机在喷雾压力为0.8 MPa、施药液量为300 L/hm^2条件下喷雾,农药分布更均匀。喷雾压力对水稻基部雾滴密度有显著影响,在水稻生长中后期,当喷雾压力低于0.8 MPa、施药液量为225~375 L/hm^2时,水稻茎秆基部雾滴密度均小于30个/cm^2。研究结果表明,喷雾压力和施药液量对自走式喷杆喷雾机稻田喷雾的农药利用率、分布均匀性及水稻茎秆基部雾滴密度有显著影响。在水稻生长前期,不宜采用高压力大水量喷雾作业;在水稻生长中后期,为增加对水稻基部病虫害的防治效果,需提高喷雾压力。     

不同助剂、喷头及喷雾压力对自走式喷杆喷雾机稻田喷雾效果的影响

以亿丰丸山3WP-500CN型号自走式喷杆喷雾机为研究对象,以诱惑红85作为指示剂,测定了6种喷雾助剂 (红太阳、倍力、迈丝、融透、印楝油和哈速腾)、3种喷头 (TEEJET-VP80015、ASJ-VP110015和LICHENG-VP11003) 以及3种喷雾压力 (0.2、0.4 和0.6 MPa) 对农药沉积利用率、药液雾化性能 (D₅₀值雾滴密度等)、雾滴分布均匀性等喷雾参数的影响,以及240 g/L噻呋酰胺悬浮剂对水稻纹枯病防治效果及水稻产量的影响。结果表明:采用TEEJET-VP80015喷头,在0.4 MPa喷雾压力条件下,助剂哈速腾雾滴分布均匀性显著高于其他助剂,变异系数为0.11,同时对雾滴估计沉积量 (45.74 μL/cm2) 与分布跨度 (1.29) 的影响显著高于其他助剂;助剂迈丝对雾滴密度 (103.78个/cm2) 和农药沉积利用率 (83.88%) 的影响均显著高于其他助剂。采用TEEJET-VP80015喷头,在未添加助剂条件下,不同喷雾压力对雾滴分布跨度、雾滴附着率和农药沉积利用率影响差异显著,其中在0.6 MPa压力下,分布跨度为1.18,雾滴附着率为33.32%,农药沉积利用率为78.19%。在未添加助剂、0.4 MPa喷雾压力条件下,喷头LICHENG-VP11003对雾滴分布均匀性的影响显著高于另外两种喷头,变异系数为0.12,同时对雾滴覆盖率 (69.37%)、雾滴估计沉积量 (42.77 μL/cm2) 和农药沉积利用率 (75.79%) 的影响也显著高于另外两种喷头。各测定条件下,240 g/L噻呋酰胺悬浮剂对水稻纹枯病的防治效果与雾化性能和雾化参数结果一致,其中添加助剂迈丝后防治效果达到89.27%,显著高于添加其他助剂,增大喷雾压力到0.6 MPa,防治效果达到88.67%,显著高于其他压力条件;采用TEEJET-VP80015喷头,在0.4 MPa喷雾压力下,水稻产量为8301 kg/hm2,显著高于人工喷雾。因此,助剂与喷头类型均对自走式喷杆喷雾机施药时的农药沉积利用率、雾滴分布均匀性以及雾滴参数和雾化效果有显著的影响,在适当的喷雾压力下添加助剂可提高农药的防治效果。     

Efficacy of aerial application ofBacillus thuringiensis to controlSpodoptera littoralis (Lepidoptera, Noctuidae) infesting soybean cultivations in Egypt

The calculated percentage of droplets deposition ofBacillus thuringiensis var.kurstaki HD-1 Dipel 2X on the foliage of soybean plants in relation to the sensitive “Ciba Geigy” papers showed to be the highest (92.4%) after ground spray application, compared to an average of 67.4, 85.8 and 89.3% following aerial application of the same preparation in spray volumes of 10, 20 and 30 l/F, respectively. Aerial application ofB. t. showed to be more effective during the first 3 days after spraying soybean cultivations and the mortality ofSpodoptera littoralis larvae varied between 36.9–67.2% in correlation to the spray volume. The volume achieving the highest and significant suppression of infestation was 20 l/F. On the other hand, the yield of soybeans obtained from plots receiving a spray volume of 30 l/F was higher compared to plots sprayed with a volume of 20 or 10 l/F, but with no significant difference when compared to those plots receiving ground spray application.     

飞防助剂和施药液量对植保无人飞机喷施雾滴沉积和棉花蓟马防效的影响

为明确飞防助剂和施药液量对植保无人飞机喷施在棉花冠层的雾滴沉积和对棉花上蓟马防效的影响,选择倍达通、功倍、杰效丰和迈丝4种飞防助剂,设置3种施药液量,通过田间试验研究了植保无人飞机喷施25%噻虫嗪水分散粒剂后其在棉花冠层的雾滴密度、覆盖率、沉积量和雾滴均匀性以及对棉花上蓟马的防效。结果表明,4种飞防助剂和3种施药液量对植保无人飞机喷施的雾滴沉积和蓟马防效均有显著影响。增加施药液量可显著增加雾滴在棉花冠层的密度与覆盖率,添加飞防助剂对雾滴密度的提升效果显著。4种助剂对农药雾滴在棉花冠层上、中、下部的覆盖率的影响趋势较为一致,与棉花冠层上部相比,对中、下部位覆盖率的影响较低。施药液量为2 L/667 m²时,添加倍达通、功倍、杰效丰、迈丝及无助剂对照的雾滴穿透性分别为46.0%、49.1%、33.6%、36.1%和44.3%,该施药液量下各处理雾滴穿透性均较好。随着施药液量增加,药后1、3、7 d对棉花蓟马的防效也显著提升。在相同施药液量下,25%噻虫嗪水分散粒剂药液中添加飞防助剂倍达通和杰效丰相较于功倍和迈丝,对棉花蓟马具有更高的防治效果。试验结果为植保无人飞机防治...     

氟虫腈药液在水稻叶片上的沉积特性研究

以氟虫腈悬浮剂为研究对象探讨了药液在水稻叶片上的沉积特性。随着雾流方向角增大,药液在稻叶上的沉积量显著增加,雾流方向角为30°、45°与60°处理时药液的沉积量分别比0°处理者提高了16.6％、39.3％与70.1％。随着雾滴体积中径(VMD)增大,氟虫腈药液在稻叶上的沉积量降低,VMD为157.3、193.2、215.4、233.7 μm 处理的药液沉积量分别比VMD 149.5 μm处理降低了16.2％、39.1％、49.5％与66.4％。施药液量少于339 L/hm2时,药液在稻叶上的沉积效率较高,为25.6％ ~28.1％,药液在稻叶上的最大稳定持留量约为 1.42 μL/cm2。较少施药液量和较小雾滴的处理,加入有机硅(150 g/hm2)后药液的沉积量可提高80％ ~150％,但施药液量增加至694.5 L/hm2 (VMD 233.7 μm)时,药液沉积量未增加。根据本实验结果,施药时采用较小雾滴和较少施药液量,雾流方向角45°~60°,并加入有机硅作为喷雾助剂,药液在稻叶上的沉积效率较高。     

Integrated control of grape black rot: influence of host phenology, inoculum availability, sanitation, and spray timing

ABSTRACT The epidemiology and control of black rot (Guignardia bidwellii) was studied from 1995 to 1999 in vineyards in Dresden and Naples, NY, where disease pressure was moderate and extreme, respectively. The efficacy of serial applications of myclobutanil, provided at 2-week intervals and varied with respect to their number and time of initiation, was examined within the context of host phenology, inoculum availability, and sanitation. At Dresden, sprays applied over 4 weeks through the immediate prebloom stage provided only 13 to 91% control of diseased clusters, despite the release of 95% of the season's ascosporic inoculum during the period of fungicidal protection. However, applications immediately prior to bloom plus 2 and 4 weeks later, which afforded protection while fruit are highly susceptible to infection, provided virtually complete control. At Naples, where mummified berries were retained in the canopy after mechanical pruning, this same regime provided only approximately 80% disease control, but applying a fourth spray 2 weeks prebloom generally improved control. Hand-pruning mummies to the ground in selected plots significantly (P 相似文献   

采用果园喷雾施药机械施药时农药有效沉积率的计算方法

针对传统农药沉积率测算方法无法精确反映果园中农药实际利用率的问题,提出一种结合果树冠层特征与叶面沉积量直接测算农药药液在果树靶标上有效沉积率的方法,以期建立一种适用于不同栽种模式的果园通用农药沉积率计算方法。首先采用传统方法计算采用风送式自走喷雾机喷雾后农药在乔化稀植型果园的地面流失率,将其结果与采用果树冠层特征与叶面沉积量相结合的方法计算的有效沉积率进行比较,再通过计算采用风送式自走喷雾机喷雾后农药在矮砧密植型果园的有效沉积率以及采用担架柱塞泵式喷雾机和植保无人飞机喷雾后农药的有效沉积率,验证本研究所提出的将果树冠层特征与叶面沉积量相结合计算农药有效沉积率方法的准确性及适用性。结果表明:基于叶面沉积量结合果树冠层特征方法计算得到的农药有效沉积率与采用传统方法计算得到的农药地面流失率结果基本一致,均能体现施药机械的农药利用率,但比较而言,本研究所提出的方法在果园植保机械喷雾施药有效利用率的影响因素方面考虑更全面,兼顾了叶面沉积量和果树冠层结构的影响,且对于不同栽种模式下的果园更具适应性。将果树冠层特征与叶面沉积量相结合进行果园农药有效沉积率的计算,可以更加真实地反映出果园农药的实际利用情况,同时通过将果树冠层结构量化为叶面积指数、冠层阴影面积等指标,可以为不同栽种模式下的果园选择适宜的植保机械,结合地面流失率的测量,计算出果园农药的飘移量,从而通过调整喷雾角度、雾滴大小、喷雾流量等参数,实现对植保机械的优化,达到精准施药的目的。     

Field evaluation of a self-propelled sprayer and effects of the application rate on spray deposition and losses to the ground in greenhouse tomato crops

BACKGROUND: In the greenhouses of south‐eastern Spain, plant protection products are applied using mainly sprayers at high pressures and high volumes. This results in major losses on the ground and less than uniform spray deposition on the canopy. Recently, self‐propelled vehicles equipped with vertical spray booms have appeared on the market. In this study, deposition on the canopy and the losses to the ground at different spray volumes have been compared, using a self‐propelled vehicle with vertical spray booms versus a gun sprayer. Three different spray volumes have been tested with a boom sprayer, and two with a spray gun. RESULTS: The vehicle with the vertical spray boom gave similar depositions to those made with the gun, but at lower application volumes. Also, the distribution of the vertical spray boom was more uniform, with lower losses to the ground. CONCLUSIONS: The vertical spray booms used in tomato crops improve the application of plant protection products with respect to the spray gun, reducing the application volumes and the environmental risks of soil pollution. Copyright © 2011 Society of Chemical Industry     

喷雾参数及助剂类型对植保无人飞机在棉花中期喷雾雾滴沉积分布的影响

采用大疆MG-1P型电动四旋翼植保无人飞机在棉花生长中期进行喷雾施药处理,探讨了喷雾参数及添加的助剂类型对农药雾滴在棉花植株叶片上沉积分布的影响。以22%氟啶虫胺腈悬浮剂及3种飞防助剂(倍达通、ND-800和G-2801)为试验药剂,在不同喷雾参数及飞防助剂条件下在棉花生长中期进行喷雾处理,以诱惑红作为药剂沉积指示剂,采用雾滴测试卡和滤纸检测雾滴沉积分布情况,利用分光光度计测定滤纸洗脱溶液的吸光度值,计算单位面积的药液沉积量,利用DepositScan软件分析雾滴密度。结果显示:植保无人飞机的飞行速度对雾滴沉积分布的影响最大,而飞行高度则对其无显著影响。添加不同助剂对棉花植株叶片正反面的雾滴沉积分布影响不同:3种助剂均可使棉花冠层上、中、下部叶片正面的雾滴密度显著提高;而对于叶片反面,则仅添加ND-800后棉花冠层上、中、下部叶片反面的雾滴密度分别增长688.9%、590.9%和327.5%,而添加G-2801与倍达通助剂则无显著影响。     

Ground deposit of pesticides in relation to the cereal canopy density

Pesticides not reaching the intended target may have negative effects on the environment and the field ecosystem. To estimate the potential ground water pollution and risk for soil-dwelling organisms it is necessary to estimate the amount of pesticide reaching the soil in different spraying situations. Literature shows that ground deposition may vary even within equal growth stages due to variations in canopy density. This paper discusses the feasibility of estimating the ground deposition of pesticides from canopy density in cereal fields. Spray experiments were carried out in wheat and barley with flat-fan nozzles of two sizes. Differences of ground deposition between the two nozzle sizes were insignificant. Adding surfactant to the spray solution significantly reduced the soil deposition in barley and in wheat cv Sleipner but not in cv Haven. A significant effect of Leaf Area Index (LAI) on ground deposition was obtained. A simple exponential model based on the LAI with an extinction coefficient of 0.48–0.50 may for many occasions satisfactorily describe the soil deposition of pesticides in cereals. Using non-destructive LAI-measurements combined with the deposition model may be useful in pesticide risk assessment on field, farm and larger regional scale and is optimising the application rate in site-specific farming. © 1999 Society of Chemical Industry     

Spray retention and distribution on apple trees

Total deposits and their distribution on bush and dwarf hedgerow apple trees, sprayed at the late dormant and full foliage stages with a copper fungicide by five different methods, were estimated by colorimetric determination of the acid-extracted copper from all the tree parts, and for comparison purposes were converted to equivalent volumes retained. The bush trees were sprayed by hand lance (4500 litresha-¹), by automatic nozzle mast sprayer (2250 litres ha^?1), by conventional air-blast sprayer at medium volume (1125 litres ha^?1) and low volume (560 litres ha^?1), and by hand-directed ultra-low-volume (ULVH) fan-assisted spinning-disc sprayer (6 litres ha^?1). The hedgerow trees were sprayed by conventional air-blast sprayer at low volume (560 litres ha^?1) and by an experimental tractor-mounted ultra-low-volume air-blast sprayer (45 litres ha^?1). At the late dormant stage, the bush trees retained only 9–22 % of the total spray applied by all methods, except that those sprayed by the hand-directed ULVH sprayer retained 57%. At the full foliage stage, when most of the spray was deposited on the leaves, retention for all methods of application was 22–37%. The hedgerow trees at late dormancy retained 6% of the spray applied in low volume and 10% of that by tractor-mounted ultra-low-volume methods, but at full foliage, retention was 25 and 63 %, respectively. On both types of tree the proportions of the spray deposited on the tree components were related to the surface areas of those components.     

The effect of different spray liquids on the foliar retention of agricultural sprays by wheat plants in a canopy

The aim of this work was to examine the effect of liquid properties on spray retention in a range of situations representative of practical pesticide application. Liquids with different physical properties were sprayed with conventional flat-fan and air-induction nozzles onto outdoor-grown wheat plants (Triticum aestivum L cv Axona) at growth stages between GS 22 and GS 35. Since total retention is affected by leaf surface as well as plant growth stage and canopy density, the experiments included spraying both single leaves and groups of plants with different canopy densities. Retention on whole plants was strongly influenced by plant growth and canopy properties. Individual leaf surfaces were not as water-repellent as was found previously for younger indoor-grown plants, reducing the effect of dynamic surface tension on retention. This, combined with the increased probability of droplets hitting foliage in a denser canopy, gave reduced differences in retention between liquids when compared with similar measurements made previously on younger plants. With a leaf area index greater than 7, retention on whole plants was almost independent of liquid. Air-induction nozzles gave lower levels of retention than flat-fan nozzles, with this difference greatest when spraying high dynamic surface tension liquids and at low crop densities.     

Assessment of canopy and ground deposits of fenitrothion following aerial and ground application in a northern ontario forest

Spray deposit patterns on simulated and live foliage of balsam fir and white birch were determined at different heights and at periphery and interior locations of the tree crown, following aerial and ground applications of fenitrothion formulations over a boreal forest near Searchmont, Ontario. Droplet size spectra and AI deposits were assessed at ground level with ‘Kromekote’ card/glass plate units. Aerial application was made with a Cessna 188 aircraft fitted with ‘Micronair’ AU3000 atomizers. For ground application, a ‘Soloport’ 423 backpack mistblower fitted with an extension tube and a diffuser nozzle at the tip was used. Deposit data on the ground samplers indicated significantly larger droplets and greater deposits from the aerial spray trial than from the mistblower treatment. However, foliar deposits at tree canopy level were only slightly higher in the former trial than in the latter. Analysis of spray deposits on simulated and live fir foliage showed definite gradients in deposit levels, decreasing from top to bottom crown, and from periphery to inner tree crown. In the birch tree crown, such gradients were not observed. The simulated leaves generally acted as better collectors of spray droplets than the natural leaves. The overall mean deposit values, expressed in ng cm^?2, showed a wide variation, although there was generally a close relationship between the deposits on the simulated and natural surfaces.     

Off-target glyphosate deposits from aerial silvicultural applications under various meteorological conditions

Aerial spray applications of the herbicide glyphosate were made over a forest canopy under various meteorological conditions. A ‘Thru Valve Boom’ dispersal system carried by a Cessna 188 fixed-wing aircraft flying at 49 m s^?1 was used to generate an aqueous spray cloud with a volume median diameter of 150 μm. Glyphosate deposits from multiple overlaid crosswind line sources released at 10 m above ground level were measured on ground sheets and artificial foliage at downwind distances between 50 and 400 m. Trials were conducted in stable, neutral and unstable atmospheric boundary layers with average wind speeds between 2·2 and 5·7 m s^?1 and vertical intensities of turbulence between 0·07 and 0·16. Linear regression lines fitted to logarithmically transformed measurements and downwind distances (x) gave statistically significant correlation coefficients (P = 0·01), and were compared by ANOVA. Glyphosate deposits on ground sheets and artificial foliage were attenuated at rates inversely proportional to x to the power 1·7-4·3. Regression line comparison showed that, in general, deposits on ground sheets decreased with increasing wind speed and intensity of turbulence, and some statistically significant differences were found in slopes and elevations of regression lines from different trials. However, deposits at the 50-m station increased with wind speed due to the large-drop cloud component. Regression line comparison for deposits on artificial foliage showed that, in general, they were highest in the intermediate wind speed-neutral stability case and similar in the high wind speed-unstable and low wind speed-stable boundary layers, although deposits at the 50-m station also increased with wind speed.     

Validation of the AGDISP Aerial Spray Deposition Prediction Model

Experimental evaluation of the computerized aerial spray prediction program (AGDISP) was conducted. Spray was applied over a flat site with a fixed-wing aircraft. Spray droplets were collected on flat cards 15 cm above the ground. Aircraft parameters were recorded during the trials. Deposits were analyzed with image analysis equipment to establish droplet-size spectra. A set of statistical parameters was applied to the measured and model-predicted droplet deposition. The results indicate that the model can predict the average droplet density and volume deposition over seven spray runs within a factor of two of actual measurements.     

4种喷雾器在茶树上喷雾效果比较

［目的］ 筛选出适合茶树病虫害防治的新型喷雾器。［方法］ 对4种喷雾器进行额定喷雾压力下喷头流量、喷雾后雾滴在茶树有效沉积量以及地面流失量的比较试验。［结果］ 静电喷雾器3WBJ 16DZ在0.5 MPa喷雾压力喷雾时喷头流量最大,为1 290 mL/min;在不同高度及距施药者不同距离的雾滴沉积分布比较中,在小区内投放相同质量指示剂的情况下,静电喷雾器3WBJ 16DZ喷雾雾滴的沉积量约为其他3种供试喷雾器喷雾雾滴沉积量的2~3倍,而其地面流失率却小于对照背负式手动喷雾器。［结论］ 通过田间试验测定,静电喷雾器3WBJ 16DZ具有施药液量少、药液沉积量高等特点,适合在茶树上推广使用。     

The use of separate root and shoot tests in the screening of herbicides for strawberries

The tolerance of strawberries to herbicides was tested by applications to the roots of plants growing in sand and by foliage applications to plants grown in compost, and compared with tolerance in the field. Dimefuron was safe as a foliar application but much more toxic than simazine when applied in sand or in the field. Metamitron caused slight injury as a foliar spray; in sand and in the field it was intermediate in toxicity between simazine and lenacil. At normal rates propachlor was safe as a foliar spray and much safer than lenacil when applied in sand. High rates had no adverse effect in the field. Ethofumesate and pendimethalin caused some temporary stunting when applied to foliage, but were less toxic than lenacil when applied to roots in sand. Field applications of both herbicides at 1–1.5 kg/ha were safe. Foliage sprays of bentazone, oxadiazon and oxyfluorfen severely damaged the sprayed leaves, but these herbicides were less active than lenacil when applied to the roots. In the field they caused severe leaf damage, but by the end of the growing season the plants had recovered. The experiments demonstrated the value of separate root and shoot activity tests for indicating which herbicides merit further field testing.     

Induced Resistance to Rice Blast by Antagonistic Bacterium, <Emphasis Type="Italic">Serratia marcescens </Emphasis>Strain B2

An antagonistic bacterium, Serratia marcescens strain B2, controlled rice blast after being sprayed onto rice phylloplane, as did the bacterial suspension when poured into rhizosphere soil of rice plants. Three days after root treatment, rice blast conidia were sprayed onto rice foliage. A week after pathogen inoculation, rice blast was suppressed and lesions caused by the pathogen decreased in size. Brown deposits were observed around sites of pathogen infection after root treatment. Induced resistance was not associated with an increase in the activitiy of peroxidase, phenylalanine ammonia lyase, tyrosine ammonia lyase, β-1,3-glucanase, β-1,4-glycosidase, N-acetylhexosaminidase or chitinase. However, lipoxygenase levels were elevated after the root treatment with strain B2 following inoculation with the pathogen. Strain B2 was not detected in rice foliage after root treatment. These data suggest that strain B2 induced resistance against rice blast caused by Pyricularia oryzae. Received 1 November 2001/ Accepted in revised form 25 January 2002