Increased susceptibility of black-currant bushes to the gall-mite vector (Phytoptusribis Nal.) following infection with reversion virus

Healthy black-currant bushes (var. Wellington XXX) and others infected systemically with a virulent strain of reversion virus were exposed equally to infestation by the gall-mite vector (Phytoptus ribis Nal.). Shoots with malformed leaves caused by mites feeding at the stem apices were virtually restricted to the virus-infected bushes. Buds infested with mites became rounded galls, which were far fewer and more localized on shoots of healthy bushes than on infected ones. Similar results were obtained in further experiments with Wellington XXX and seven other varieties. Bushes infected systemically with an avirulent strain of reversion virus developed more galls than healthy bushes, but fewer galls than bushes infected with a virulent strain. The young buds of virus-infected bushes were 170 times more susceptible to dispersing mites than those of healthy bushes. The axillary buds of healthy bushes resisted infestation and the apical meristems were virtually inaccessible to mites, whereas the axillary and apical buds of virus-infected bushes were invaded readily. An experiment with bushes var. Cotswold Cross that were either healthy or partially or completely infected with reversion virus was retained for two years. Each year there was a relationship between symptom expression and mite infestation; only shoots with chronic virus symptoms developed mite-affected leaves and numerous galls. Virus infection increased the vulnerability and accessibility of the apical and axillary buds by decreasing the density of hairs on the stems and leaves. Infected bushes also presented a greater catchment area to dispersing mites and more shoots and buds were available for colonization than on healthy bushes. The interactions between virus, host and vector are discussed, together with their implications in nature, in experimental design and in disease control.     

Field experiments on the spread of black currant reversion virus and its gall mite vector (Phytoptus ribis Nal.)

In two experiments the spread of reversion virus from a row of systemi-cally infected black currant bushes heavily infested by the gall mite vector (Phytoptus ribis Nal.) was predominantly in the direction of the winds prevailing during the dispersal period. On each side of the sources there was a curvilinear decrease of galled buds and of virus infection as distance increased. In another experiment a central source of mites and virus was surrounded by concentric hexagons comprising alternate rows of healthy and virus-infected bushes. At leaf-fall, galls were forty times more numerous on virus-infected than on healthy bushes; plants in the sector downwind developed the most galls and those upwind the least. On both healthy and virus-infected bushes in each sector, the incidence of galls decreased with increasing distance from the source. The gradients of infestation were steeper on healthy than on virus-infected bushes, especially in sectors upwind from the source. In some sectors the infestation gradients were distorted because many of the virus-infected bushes were so heavily infested that most of the buds became galled. The spread of virus to initially healthy plants decreased from 100 to 75% near the source, to zero at the periphery. More bushes became infected downwind from the source than upwind. In each experiment more bushes developed galls than later produced symptoms of virus infection, the incidence of which was positively correlated with the number of galls recorded the previous winter.     

Potential of pigeon pea as a trap crop for control of fruit worm infestation and damage to okra

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Phytoseiid mites (Acari: Phytoseiidae) on apple trees and in surrounding vegetation in southern Finland. Densities and species composition

Leaf samples were collected from sprayed (n=29) and unsprayed (n=19) apple orchards, from the surrounding vegetation (n=58) and from one arboretum (n=12), altogether from 46 plant species (1–5 samples each). The density of phytoseiid mites averaged 1.2 mites/leaf on unsprayed apple trees, but only 0.06 mites/leaf on sprayed trees. The phytoseiid density exceeded 1/leaf onAesculus hippocastani, Aristolochia macrophylla, Corylus avellana, Fragaria vesca, Frxinus excelsior, Juglans cinerea, Pterocarya rhoifolia, Ribes nigrum, Rubus odoratus, Sorbus aucuparia, S. thuringiaca, Tilia×euchlora andUlmus glabra. Other common trees and bushes inhabited by phytoseiids wereCrataegus coccinea (0.2 mites/leaf),Prunus padus (0.7),Salix caprea (0.4), andTilia cordata (0.9).Twelve species of phytoseiid mites were found, of which ten occurred on unsprayed apple trees. The most widely distributed species on apple trees werePhytoseius macropilis (in 79% of unsprayed samples),Euseius finlandicus (74%),Paraseiulus soleiger (53%),Paraseiulus triporus (37%),Amblyseius canadensis (26%) andAnthoseius rhenanus (26%). The highest densities on apple trees were found in populations ofE. finlandicus (mean 0.7 mites/leaf),Ph. macropilis (0.5) andA. canadensis (0.5). On sprayed apple trees,E. finlandicus, Pa. soleiger andPh. macropilis occurred most commonly, but their mean densities were under 0.1/leaf. Almost no phytoseiids were found in orchards sprayed with oxydemetonmethyl before blooming of apple.On other plants,E. finlandicus occurred most commonly (on 33 plant species) and in the highest densities, followed byPh. macropilis (14),Pa. soleiger (12),Pa. triporus (12) andAn. rhenanus (7).Seiulus aceri andParaseiulus talbii were identified as new phytoseiid species in Finland. It is concluded that deciduous trees and bushes in forest margins around orchards can serve as important reservoirs for phytoseiid mites, and that the dominant species in these plants would migrate into and colonize the orchards if the use of harmful chemicals were restricted.     

Some effects of spraying with thiabendazole on the susceptibility of sugar beet to yellowing viruses and on their vector, Myzus persicae (Sulz.)

In a field experiment fewer sugar-beet plants became infected with aphid-transmitted yellowing viruses in plots that had been sprayed with solutions of thiabendazole lactate than in water-sprayed plots, after exposure to natural infestation with aphids. Subsequent glasshouse tests showed that foliar sprays of o·o1 % thiabendazole lactate in water significantly reduced the proportion of inoculated sugar-beet plants which became infected with beet yellows virus (BYV) or beet mild yellowing virus (BMYV) after inoculation with viruliferous Myzus persicae (Sulz.). This effect on virus transmission was not apparently due to a direct insecticidal action of thiabendazole, because adult aphids usually survived equally well on sprayed and unsprayed plants. Treatment of test plants with thiabendazole did not affect the transmission of beet mosaic virus to them by M. persicae. The fecundity of M. persicae was greatly reduced by transferring them to plants which had been sprayed with thiabendazole or by spraying them with thiabendazole before transfer to unsprayed plants. The fertility of adult Aphis fabae Scop, was also reduced by spraying with thiabendazole. The mechanisms whereby thiabendazole affected fecundity of aphids and transmission of viruses are not understood.     

The incidence of rosette disease in groundnut in relation to plant density and its effect on yield

Trials are described in which the relationships between plant density, rosette disease incidence and the yield and quality of groundnuts were investigated on sprayed and unsprayed groundnut plants. During growth, the number and percentage of sprayed and unsprayed plants showing symptoms of rosette disease was significantly greater at low plant populations than at high. At harvest, in general on unsprayed plots the numbers attacked were also greater at low plant populations, but on the sprayed plots the results were inconsistent. The percentage attack at harvest was much lower on sprayed plots at all plant populations. Menazon used as a seed dressing did not affect the incidence of the disease but used as a spray it significantly reduced the amount of disease found. The spray was applied at a rate of 294 g a.i./ha, four times at 10-day intervals, the first spray being applied 10 days from germination. Spraying controlled secondary spread of the virus within the crop and appeared to reduce the severity of early attack. There was a marked improvement of yields and quality of nuts from sprayed plots. Plant density did not affect quality of the groundnuts obtained, but yields per ha were highest on both sprayed and unsprayed plots at the highest plant densities (seed rate up to 134 kg/ha).     

Effects of eyespot on the yield of winter wheat

In two experiments, on Julia and Zephyr spring barley, evidence was obtained that the development of powdery mildew in sprayed plots depended very much on their proximity to unsprayed crop. The effective period of control achieved with one spray was greater where plots were well separated from unsprayed crop than where they were surrounded by or very close to unsprayed crop. There is probably a risk that small plot experiments may not only underestimate the potential effectiveness of fungicides in agricultural practice, but also give misleading information on optimal spray timing.     

The effects of different external nitrate concentrations on growth of Avena sativa cv. Amuri treated with diclofop-methyl

Avena sativa cv. Amuri fed either low or high nitrate was sprayed with diclofop-methyl (1 kg a.i. ha^-1) at the three leaf stage. The short term effects of the herbicide on chlorophyll concentration of leaves (laminae) and short and long term effects on d.wt of the component plant parts were determined by comparison with unsprayed plants. For unsprayed and sprayed plants, total leaf d.wt approximately doubled during the first twelve days after commencing treatments. Growth was substantially greater at high nitrate than low nitrate. For unsprayed plants, the increase in total leaf d.wt was due primarily to growth of leaf 3 but for sprayed plants it was due to growth of leaves 1 and 2. Twelve days after commencing treatments, d.wt of leaves 1 and 2 was substantially greater for sprayed plants than for unsprayed plants given similar nitrate, while chlorophyll concentration was substantially less. Leaf 3 d.wt and chlorophyll concentration were substantially greater in unsprayed plants than in sprayed plants given similar nitrate. For unsprayed plants, values were greater at high nitrate than low nitrate, for sprayed plants the converse was the case. Forty nine days after commencing treatments, unsprayed plants had a greater total plant d.wt than sprayed plants given similar nitrate. Total plant d.wt for unsprayed plants was greater at high nitrate than low nitrate, the opposite was the case for sprayed plants. Unsprayed plants at both nitrate levels and sprayed plants given low nitrate produced seed heads but sprayed plants given high nitrate did not. Diclofop-methyl at a rate of 0.3 kg a.i. ha^-' stopped seed head production at high nitrate. Retention and uptake of diclofop-methyl were not significantly different at low and high nitrate. At 1 kg a.i. ha-^l diclofop-methyl, plants switched from low to high nitrate at spraying showed damage similar to that shown by plants given high nitrate throughout. Addition of 200 μg GA into the leaf sheaths two days prior to spraying increased the efficacy of diclofop-methyl at low nitrate. It is proposed that increased efficiency of diclofop-methyl at high nitrate is due to increased leaf damage caused by a greater rate of leaf expansion.     

Accumulation and persistence of a nuclear polyhedrosis virus of the cabbage looper in the field

A nuclear polyhedrosis virus of the cabbage looper, Trichoplusia ni, was applied to foliage of Fall-planted broccoli and cabbage plants. Soil bioassays demonstrated that appreciable quantities of active virus accumulated in the upper 1 cm of the soil of plots sprayed with 10, 20, and 100 larval equivalents (LE)/acre as well as in unsprayed plots. After completion of the spray program, soil from plots treated with 8 foliar applications of 10 LE/acre contained only slightly more virus than the soil from unsprayed plots, but considerably more virus accumulated in plots treated with 20 and 100 LE/acre. The accumulation of virus continued after the completion of spraying and considerable quantities of active virus persisted through the winter.     

Codling moth granulosis virus: effects of its use on some other orchard arthropods

In four field trials from 1978 to 1980, sprays of codling moth granulosis virus (CpGV) plus 1·0% skimmed milk powder did not significantly affect damage to fruit by leaf rollers (tortrix moths). In laboratory tests, survival of larvae of the leaf roller Archips podana fed on leaves sprayed with CpGV plus milk was unaffected and they grew faster than on unsprayed leaves, because of the milk deposits. This might increase damage by A. podana if CpGV plus milk were applied during the feeding period of this species. In one field trial an unusual infestation of fruit by larvae of pith moth Blastodacna atra was not affected by CpGV. Azinphos-methyl significantly reduced damage by B. atru and, in one field trial where sprays were correctly timed, that by leaf rollers. CpGV had no consistently significant effects on numbers of fruit tree red spider mite Panonychus ulmi or its predators, whereas azinphos-methyl induced outbreaks of P. ulmi by killing its predators.     

Dispersal and gene flow of pesticide resistance traits in phytoseiid and tetranychid mites

Dispersal and gene flow of pesticide resistance traits in phytoseiid and tetranychid mites are discussed relative to their biologies and resistance management. The focus is on deciduous fruit-tree crops whereTyphlodromus pyri Scheuten andMetaseiulus occidentalis (Nesbitt) can effectively control spider mite pests. Oregon populations ofM. occidentalis were more dispersive thanT. pyri, as evidenced by movement to small apple trees placed inside and outside of commercial apple orchards. This difference was corroborated by the spatial distributions of organophosphate resistance in populations from sprayed orchards and nearby unsprayed habitats:T. pyri showed patchy, local patterns of resistance whileM. occidentalis showed more regional, homogeneous trends. Gene flow among populations was estimated from allozymic variation ofT. pyri. Intra- and inter-population genetic variation was high enough to prevent population differentiation. Thus, allozymic estimates of gene flow were higher than that indicated by pesticide resistance patterns.Dispersal inTetranychus urticae Koch is also discussed relative to resistance evolution. Immigration of resistant phenotypes from crops or other sprayed habitats can increase the frequency of resistance. Immigration of susceptible individuals from surrounding unsprayed habitat into a sprayed crop can slow resistance or lead to its reversion, depending on the level of gene flow between populations. Dispersal within crops can have the same effect if susceptibles come from a refuge. In pears, immigration of susceptibleT. urticae from nearby habitat and groundcover aided in reversion of organotin resistance. Experiments on resistance management tactics forT. urticae are discussed.     

Efficacy and phytotoxicity of lime sulphur in organic apple production

Curative and preventive efficacy and phytotoxicity of lime sulphur spray schedules, based on a warning system, were evaluated in the Netherlands during two growing seasons under field conditions. In most cases, lime sulphur treatments applied either curatively or preventively resulted in significantly lower scab damage on both the leaves and fruits compared to wettable sulphur treatments. However, all lime sulphur treatments showed high phytotoxicity values, reduced leaf size and had a tendency to a reduced yield quality compared to all other treatments. For curative schedules of lime sulphur on scab control, phytotoxicity and yield did not differ significantly from preventive schedules of lime sulphur. However, the use of a warning system combined with curative schedules of lime sulphur saved one and two lime sulphur sprays in 2000 and 2001, respectively, compared to the preventive treatments of lime sulphur. Our results demonstrated that a curative spray programme with lime sulphur at 0.75–2%, applied 35–45 h after predicted infection periods, can provide effective primary apple scab control, but no benefit in either yield or fruit quality was reached under organic growing conditions. Moreover, research herein clearly showed that organic growers are forced to find a balance between good efficacy and phytotoxic effects of lime sulphur.     

Effectiveness of GF-120 fruit fly bait spray applied to border area plants for control of melon flies (Diptera: Tephritidae)

In a field study in Hawaii, color-marked protein-deprived and protein-fed female melon flies, Bactrocera cucurbitae Coquillett, were released within canopies of unsprayed sorghum plants (a nonhost of melon flies) outside of a border area of unsprayed or bait-sprayed sorghum plants or open space that surrounded cucumbers, a favored host of melon flies. Application of bait spray to sorghum or sugarcane surrounding host plants of melon flies is a common practice for melon fly control in Hawaii. GF-120 Fruit Fly Bait spray proved very effective in preventing protein-deprived females from alighting on cucumbers (23% of released females were observed dead on bait-sprayed sorghum; 0% were observed alive on cucumbers), but proved less effective in suppressing protein-fed females (14% of released females were observed dead on bait-sprayed sorghum; 11% were observed alive on cucumbers). No females were found dead on unsprayed sorghum. Compared with open space surrounding cucumbers, the presence of unsprayed sorghum as surrounding border area neither significantly enhanced nor significantly inhibited the ability of either type of female with respect to finding cucumbers. Greenhouse cage assays revealed that compared with droplets of water, droplets of GF-120 Fruit Fly Bait spray were highly attractive to protein-deprived females within 1 h of bait spray application to sorghum, but lost about half of their attractiveness within 5 h and all of it within 24 h under the dry greenhouse conditions used for maintaining baited-sprayed sorghum plants in these assays. Laboratory cup assays showed that bait spray droplets remained highly toxic to protein-deprived females 24 h after application, but lost nearly half of their toxicity within 4 d under laboratory exposure and nearly all of it after approximately 8 mm of rainfall. Combined findings suggest that application of GF-120 Fruit Fly Bait spray to nonhost plants for melon fly control either be made often enough to overcome loss of attractiveness of bait spray droplets to females or that bait spray be applied to nonhost plants that are themselves attractive to the females.     

Managing the pepper maggot (Diptera: Tephritidae) using perimeter trap cropping

A perimeter trap crop barrier of hot cherry peppers, border-row insecticide applications, and a combination of the two management strategies were evaluated to see if they could protect a centrally located main crop of bell peppers from oviposition and infestation by the pepper maggot, Zonosemata electa (Say). In large plots, the main cash crop of bell peppers was protected from the majority of the oviposition and infestation by all three barriers. The combination sprayed/trap crop barrier provided the best protection against both oviposition and infestation and resulted in over 98% pest-free fruit at harvest. Maggots infested only 1.7% of the main crop fruit when protected by a sprayed or unsprayed trap crop barrier, compared with 15.4% in control plots. The perimeter sprayed/trap crop strategy was employed in three commercial fields in 2000 and 2001. The combination barrier resulted in superior insect control and reduced insecticide use at all commercial locations, compared with the same farms' past history or to farms using conventional and integrated pest management (IPM) methods. Economic analysis showed that the technique is more cost effective and profitable than relying on whole-field insecticide applications to control the pepper maggot. Farmer users were surveyed and found the perimeter trap crop technique simple to use, with many hard-to-measure benefits associated with worker protection issues, marketing, personnel/management relations, pest control and the environment. Use of the perimeter trap crop technique as part of an IPM or organic program can help improve crop quality and overall farm profitability, while reducing pesticide use and the possibility of secondary pest outbreaks.     

Yield loss of faba bean (Vicia faba) due to chocolate spot (Botrytis fabae) in sole and mixed cropping systems in Ethiopia

Two field experiments were conducted during 2004 and 2005 cropping seasons at Adet Agricultural Research Center, Ethiopia to assess yield losses caused by chocolate spot(Botrytis fabae) of faba bean in sole and mixed cropping systems using two cultivars. Cropping systems were sole faba bean (FB), faba bean mixed with field pea (FB: FP), barley (FB: BA) and maize (FB: MA). Mancozeb was sprayed at the rate of 2.5 kg a.i/ha at 7-, 14- and 21-day interval to generate different levels of chocolate spot disease in all the four cropping systems, and unsprayed control was also included. The treatments were arranged in a randomised complete block design (RCBD) with four replications. FB: MA mixed cropping significantly reduced disease severity and the area under disease progress curve (AUDPC) and increased faba bean grain yield. The highest faba bean grain yield among the three mixed croppings under different spray schedules was obtained from FB: MA mixed cropping in both 2004 and 2005 (2.56 and 3.74 t/ha, respectively) cropping seasons. There were highly significant yield differences (P < 0.05) among the spray intervals of mancozeb in both seasons. The highest grain yield (4.9 t/h) was recorded from the 7-day spray interval in 2005. The unsprayed faba bean had a lower grain yield (1.9 t/ha in 2004 and 2.3 t/ha in 2005) compared to the sprayed plots. The highest relative yield loss (67.5%) was calculated in 2005 from FB: FP mixed cropping in unsprayed plots. The relative yield losses in the unsprayed plots were in the range of 35.8–41.5% in 2004 and 52.6–67.5% in the 2005 cropping season. Severity and AUDPC were inversely correlated with faba bean grain yield. Significant differences were recorded in the 100-seed weight and days to maturity (DM). The unsprayed plots had shorter DM ranging from 126 to 128.5 day (except FB: MA mixed cropping) in 2004 and 122–123.9 days in 2005. In the sprayed plots DM was relatively longer than the unsprayed plots. A higher seed weight was recorded in the sole FB (56 g) and FB: MA (55 g) mixed cropping, and the lowest value of 100-seed weight was recorded from FB: FP (53 g) mixed cropping. The productivity of the mixed cropping evaluated by land equivalent ratio (LER) exceeded that of sole cropping. Faba bean grain yield was highly influenced by the severity of chocolate spot. The disease affects the DM, forcing early maturing of the plants.     

Control of contamination of potatoes with air-borne Erwinia carotovora by foliar application of copper oxychloride

In field experiments in 1983 and 1984, micropropagated plants of cv. Désirée planted in soil tested and found free of erwinias became contaminated with airborne erwinias, mostly E. carotovora pv. carotovora, in September when rain was more abundant, but not earlier. Control of contamination of progeny tubers harvested in September and October was achieved by spraying plants with copper oxychloride (‘Cuprokylt’; 5 g litre^-1) twice weekly from June or July but not from August nor by weekly or fortnightly treatments from June. Bactericidal activity of copper in the effective spray regimes was not expressed on the leaves or in the soil and contamination was similar in the sprayed and unsprayed treatments. In contrast, multiplication of erwinias in senescent leaves on the soil surface (leaf debris) was inhibited in the sprayed treatment but not in the unsprayed treatment and population numbers of c. 10³ cells g^-1 fresh weight were detected. It is suggested that fewer erwinias would be washed from leaf debris by rain in the sprayed than in the unsprayed treatment to contaminate the progeny tubers.     

Experiments on the time of application of insecticide to decrease the spread of yellowing viruses of sugar beet, 1954-66

Sprays of demeton-methyl insecticide decreased the spread of yellowing viruses by aphids in sugar-beet crops in England. Between 1957 and 1960, when yellows was prevalent, the incidence, assessed as ‘infected-plant-weeks’, was decreased by 36–41 % by one spray, depending on when it was applied, and by 55 % by two sprays, giving average yield increases of 1½ and 2 ton/acre of roots respectively. Between 1962 and 1966, when yellows spread less, a spray at the time when growers were advised to spray by the British Sugar Corporation decreased yellows incidence by 37 %, whereas sprays 2 weeks earlier or later decreased it by 24 % and 25 % respectively. Between 1958 and 1966 an annual average of 160000 of the country's 440000 acres of sugar beet has been sprayed, often to control Aphis fabae as well as to check the spread of yellows. A spray gives a profitable yield increase when yellows incidence in unsprayed plots is 20 % at the end of August.     

Aerial application of mixed virus formulations to control joint infestations of Panolis flammea and Neodiprion sertifer on lodgepole pine

An aerial spray using mixed formulations of two viruses, Panolis flammea nuclear polyhedrosis virus (NPV) and Neodiprion sertifer NPV was conducted against mixed populations of the two pests, P. flammea and N. sertifer on lodgepole pine. These were compared with single virus formulations sprayed against their respective host pests and an unsprayed control. One hectare plots of 14 yr old pine were sprayed by helicopter using ultra low volume techniques. Larvae from each plot were assessed weekly for virus and this showed that the mixed formulations gave the same level of control as separate applications of each NPV. Levels of infection in P. flammea reached 95 – 100% 9 wk post-spray, and in N. sertifer reached 100% 6 wk post-spray. Later P. flammea pupal sampling showed no viral infection in the control but significant levels in sprayed plots, which ranged from 37–9% in the plot sprayed with the high dose of N. sertifer NPV to 75% in the plot sprayed with the low dose of NsNPV.     

Determining an economic injury level for the persea mite,Oligonychus perseae,a new pest of avocado in Israel

The persea mite, Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae), a pest of avocado, was first discovered in Israel in the autumn of 2001. It has since spread to most avocado growing areas in Israel. To establish an economic injury level (EIL), based on the percentage of leaf area damaged (PLAD), we conducted an extensive field study. For three consecutive seasons we created distinct pest infestation levels on the Hass avocado cv., by applying acaricides (spirodiclofen and abamectin) at 50, 100, and 250 mites per leaf levels, along with non‐sprayed controls in a replicated block design. At harvest time we evaluated the level of leaf damage and fruit yields across treatments. In two out of the 3 years, trees sprayed at 50 and 100 mites per leaf levels had similar PLAD values, differing from trees treated at the 250 mites per leaf level and the non‐treated control, the latter pair also being similar. Over the 3 years, mean yield attained at the two higher infestation levels was reduced by 20% in comparison to the mean yields recorded for plots sprayed at the lower thresholds. Accordingly, we suggest that scouts adopt an action threshold (AT) of 50–100 mites per leaf. Future research is needed to refine this AT. Mean annual cumulative mite days (CMDs) of the two higher levels was ca. 13500 ± 700 per leaf. Using the linear regression equation PLAD = 0.0009CMDs + 2.42, describing leaf damage as a function of CMDs, we estimated an EIL of ca. 15 PLAD.     

Evaluation of Beauveria bassiana and Metarhizium anisopliae for Controlling Chilo partellus (Lepidoptera: Crambidae) in Maize

Maize (variety Katumani) was planted in a greenhouse and plants were infested with 20 Chilo partellus second instar larvae 3 and 4 weeks after plant emergence. One isolate of Beauveria bassiana (BB-01) and four isolates of Metarhizium anisopliae (PPRC-4, PPRC-19, PPRC-61 and EE-01) were sprayed onto the leaf whorl at 2×10⁸ conidia/mL 24 h after infestation. Leaf damage by the larvae was greatly reduced by the treatments. The mean daily temperature and relative humidity in the greenhouse ranged from 10 to 35°C and 30 to 90%, respectively. The growth of infested unsprayed plants was less than that of fungi treated plants. Stem tunneling (1-5%), deadheart (0-33%), number of attacked nodes (0.3-2.5) and holes (0.2-3.3) were also reduced in plants sprayed with conidial suspensions. Isolates PPRC-4, PPRC-19 and PPRC-61 seemed to be the best candidates for further development.