Chemical treatments were evaluated for efficacy against spe- cific ant pests in two perennial fie... more Chemical treatments were evaluated for efficacy against spe- cific ant pests in two perennial field crop systems. A directed spray of Lorsban applied in grape vineyards resulted in significant reductions of Formica per- pilosa Wheeler (Hymenoptera: Formicidae) for 9 wk. Significant reductions in the number of foraging Argentine ants, Linepithema humile (Mayr) (Hy- menoptera: Formicidae), were obtained in citrus for the 4-mo duration of a test with a liquid bait delivery system containing either 0.0001% fipronil or thia- methoxam in 25% sucrose water.
Annals of the Entomological Society of America, 1975
... Host Race Formation Among Sympatric Apple, Walnut, and Plum Populations of the Codling Moth, ... more ... Host Race Formation Among Sympatric Apple, Walnut, and Plum Populations of the Codling Moth, Laspeyresia pomonella. Authors: PHILLIPS ...
The citrus bud mite, Aceria sheldoni (Ewing), has a reputation as being a serious pest of lemons ... more The citrus bud mite, Aceria sheldoni (Ewing), has a reputation as being a serious pest of lemons in California, although recent studies failed to reveal a consistent economic impact. To resolve some previous inconsistencies, we evaluated the economic value of treatments to suppress citrus bud mite populations on a commercial scale over 3 yr. Experiments were conducted in 6 groves and included 2 treatments of 100 trees each. In 1 treatment (treated), trees were managed according to conventional commercial practices and included 1Ð2 annual applications of narrow-range oil to suppress citrus bud mite populations. In the other treatment (untreated), experimental trees were managed identically as treated trees, except that oil spray applications for citrus but mite were withheld. Bud mite density and incidence on experimental trees were monitored monthly, as were the number of fruit and the proportion of distorted fruit. Fruit from all 100 trees in each treatment per grove were commercially harvested, graded and packed. Crop volume, grade, size distribution, and value were compared across treatments. Although oil sprays effectively suppressed citrus bud mite populations, this yielded no consistent beneÞt to crop volume, grade, or value. For all groves, the value of fruit from treated trees was not signiÞcantly greater than that from untreated trees, even before the cost of oil sprays was subtracted. In 4 of 6 cases, crop value was numerically lower in the treated treatment. Results suggest that the oil sprays themselves may have had deleterious effects on fruit initiation and abortion. The potential phytotoxicity of oil sprays, although long known, may not be fully considered in contemporary treatment decisions for the citrus bud mite.
The effect of high population densities of citrus bud mite, Aceria sheldoni (Ewing), on the quant... more The effect of high population densities of citrus bud mite, Aceria sheldoni (Ewing), on the quantity and quality of lemon yields was studied for 4 yr in four commercial groves in coastal southern California. There were two treatments in each grove: treated plots where bud mite was suppressed with acaricide treatments whenever infestation levels increased markedly, and untreated plots where bud mite was not controlled. Average percentage of axillary buds infested with citrus bud mite was 7-15% in treated plots and 45-70% in untreated plots over the 4-yr period. Citrus bud mite feeding results in distortion of fruit shape which can result in commercial downgrading. Citrus bud mite control significantly reduced fruit distortion in all four groves and significantly improved commercial packout in three of the four groves. However, significantly less distortion in fruit was not detected in treated trees until harvests ≥10-13 mo after the initial acaricide treatment (lemons in coastal California are harvested three or four times per year). This supports the hypothesis that distortion in fruit is caused by citrus bud mite feeding on embryonic fruit tissue in the buds; once fruit set, they are unaffected by further citrus bud mite feeding. Up to 21 mo after the first acaricide treatments, the cumulative yield did not differ significantly between treated and untreated plots. In two of the four groves, in the eight harvests between 24 and 48 mo after the first acaricide treatments, the cumulative yield was often significantly greater (9-13% greater) from treated than from untreated trees. The other two groves showed no significant differences in cumulative yield between treated and untreated trees up to the time of the last harvest (28 and 49 mo after the first acaricide treatment). In two groves, economic loss justified the cost of bud mite suppression, and in two groves, the cost of suppression exceeded the economic benefit of suppression.
and Emer gency Project established a statewide monitoring program to determine the extent of the ... more and Emer gency Project established a statewide monitoring program to determine the extent of the olive fruit fl y's occur rence, track its seasonal biology and evaluate monitoring tools. Fly popu lations and infestations can reach high levels throughout California but tend to be lower in the San Joaquin Valley. Trap captures typically exhibit a bimodal distribution with peaks in the spring and fall. Olive infestation is related to fl y densities, climate and fruit size. Gravid, mated females vary in density throughout the year but are present at some level yearround. The data is being used to develop models that will better predict when the adults are active and olives are at risk.
... large necrotic areas but >50% ofthe bud remains suc-culent and undamaged; 3, moderate ... more ... large necrotic areas but >50% ofthe bud remains suc-culent and undamaged; 3, moderate to severe damage, necrotic areas extensive, <25% of the bud is still succulent and healthy; 4, severe dam-age, outer bud scales are all dark, hard and dry, no green succulent tissue left ...
Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in ou... more Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in our understanding of this pest. We now know the area of origin of the avocado thrips and have compiled an inventory of other potential pest thrips species on avocados in Mexico and Central America. Trials have helped us to identify several selective insecticides for use in treating avocado thrips in orchards. We have also determined the relationship between thrips densities on leaves and fruit scarring, and are studying cultural and biological control practices for use in an evolving integrated pest management (IPM) program.
Use of abamectin for avocado thrips, Scirtothrips perseae, also has effects on the persea mite, O... more Use of abamectin for avocado thrips, Scirtothrips perseae, also has effects on the persea mite, Oligonychus perseae, and avocado bud mite, Tegolophus myersi, in Ventura County, California. In this study individual trees were treated with the standard insecticides for thrips, sabadilla (Veratran D) and abamectin (Agri-Mek), using a backpack sprayer, or left untreated. Sabadilla reduced S. perseae numbers on young and old leaves but failed to reduce O. perseae and T. myersi numbers. Abamectin significantly reduced numbers of all three pests. In addition, abamectin reduced the amount of leaf drop associated with O. perseae feeding. In a companion trial, where abamectin and sabadilla were applied by ground rig in one orchard and another orchard was left untreated, there were no differences in T. myersi populations. When all three pests are present, the use of abamectin may be a more efficient strategy than the use of sabadilla.
Scirtothrips perseae Nakahara was discovered attacking avocados in California,USA, in 1996. Host ... more Scirtothrips perseae Nakahara was discovered attacking avocados in California,USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a ‘‘classical’’ biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (\u3e1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (\u3e1300 m)....
Pruning as a cultural practice has been increasingly used in Southern California avocado orchards... more Pruning as a cultural practice has been increasingly used in Southern California avocado orchards. This practice promotes the production of flush growth, which is the preferred food source of avocado thrips (Scirtothrips perseae Nakahara). Currently, most pruning activities take place in January, February or March. To determine when pruning ‘Hass ’ avocado least affects fruit set and minimizes avocado fruit relates monthly pruning times in 2002 to the presence of flushing leaves as a food source for avocado thrips, the numbers of immature avocado thrips, and to the 2002 and 2003 fruit set. Pruning between January and May promoted the prolonged presence of flush during fruit set and early fruit development through August and delayed the hardening of the leaves. With the grower's IPM program, which used 4 chemical treatments to suppress avocado thrips, the number of thrips was significantly higher on trees pruned
Project history These studies are also known as (a part of) BIOSA, a project aiming to develop a ... more Project history These studies are also known as (a part of) BIOSA, a project aiming to develop a “Biologically Intensive Orchard System for Avocado ” which would ultimately integrate non-chemical pest control methods and cultural management into a suggested method for growing avocado with fewer pesticides. Pruning, mulching, planting several plant species on the orchard floors, different means of fertilization and release of potential natural enemy (NE) agents for biological control were planned for subsequent years after establishing the current practices for managing avocado thrips problems and identifying the species and numbers that make up the resident natural enemy populations in avocado groves. Time restrictions and limitations of manpower have resulted in this 2-year survey of avocado thrips and their potential natural enemies in 2003 and 2004, with correlations of natural enemies with distance from the coastline and fraction of orchard floor covered with leaf duff, living o...
aged by crows. From these estimates, we calculated a 3 to 4% loss in production, about 40 pounds ... more aged by crows. From these estimates, we calculated a 3 to 4% loss in production, about 40 pounds per acre, for those returning the survey. In estimating overall loss, average losses in the range of 1 to 5% and 6 to 10% were reported by 28% and 26% of the growers, respectively; 24% of the growers indicated losses in the range of 11 to 50%.
The vineyard training/pruning system can dramatically influence the amount of Botrytis bunch rot.... more The vineyard training/pruning system can dramatically influence the amount of Botrytis bunch rot. Trying to achieve better light reception can impede air movement and result in &eater incidence of rot. Researchers recently concluded that growers can manage a vine's microclimate to reduce the development of Botrytis bunch rot in vineyards by increasing the air movement around clusters. Differences in Botrytis severity were further noted during a study of different trellis heights and different training and pruning methods in a Santa Maria white riesling vineyard. Previous data had focused on vine yield and fruit composition parameters. In 1985 the study was expanded toincludetheincidence of Botrytis bunch rot among the differently established vines. Insufficient air circulation can promote Botrytis bunch rot in grapes. Proper pruning keeps the fruit bunches clear of enveloping leaves.
... continuously agttated until essentially all the mixture was incorporated in or on the twine. ... more ... continuously agttated until essentially all the mixture was incorporated in or on the twine. Another formulation, which we call "ant tape," was prepared in the followingway. <?neto three strands of cotton twine, permeated Withrepellent ...
Chemical treatments were evaluated for efficacy against spe- cific ant pests in two perennial fie... more Chemical treatments were evaluated for efficacy against spe- cific ant pests in two perennial field crop systems. A directed spray of Lorsban applied in grape vineyards resulted in significant reductions of Formica per- pilosa Wheeler (Hymenoptera: Formicidae) for 9 wk. Significant reductions in the number of foraging Argentine ants, Linepithema humile (Mayr) (Hy- menoptera: Formicidae), were obtained in citrus for the 4-mo duration of a test with a liquid bait delivery system containing either 0.0001% fipronil or thia- methoxam in 25% sucrose water.
Annals of the Entomological Society of America, 1975
... Host Race Formation Among Sympatric Apple, Walnut, and Plum Populations of the Codling Moth, ... more ... Host Race Formation Among Sympatric Apple, Walnut, and Plum Populations of the Codling Moth, Laspeyresia pomonella. Authors: PHILLIPS ...
The citrus bud mite, Aceria sheldoni (Ewing), has a reputation as being a serious pest of lemons ... more The citrus bud mite, Aceria sheldoni (Ewing), has a reputation as being a serious pest of lemons in California, although recent studies failed to reveal a consistent economic impact. To resolve some previous inconsistencies, we evaluated the economic value of treatments to suppress citrus bud mite populations on a commercial scale over 3 yr. Experiments were conducted in 6 groves and included 2 treatments of 100 trees each. In 1 treatment (treated), trees were managed according to conventional commercial practices and included 1Ð2 annual applications of narrow-range oil to suppress citrus bud mite populations. In the other treatment (untreated), experimental trees were managed identically as treated trees, except that oil spray applications for citrus but mite were withheld. Bud mite density and incidence on experimental trees were monitored monthly, as were the number of fruit and the proportion of distorted fruit. Fruit from all 100 trees in each treatment per grove were commercially harvested, graded and packed. Crop volume, grade, size distribution, and value were compared across treatments. Although oil sprays effectively suppressed citrus bud mite populations, this yielded no consistent beneÞt to crop volume, grade, or value. For all groves, the value of fruit from treated trees was not signiÞcantly greater than that from untreated trees, even before the cost of oil sprays was subtracted. In 4 of 6 cases, crop value was numerically lower in the treated treatment. Results suggest that the oil sprays themselves may have had deleterious effects on fruit initiation and abortion. The potential phytotoxicity of oil sprays, although long known, may not be fully considered in contemporary treatment decisions for the citrus bud mite.
The effect of high population densities of citrus bud mite, Aceria sheldoni (Ewing), on the quant... more The effect of high population densities of citrus bud mite, Aceria sheldoni (Ewing), on the quantity and quality of lemon yields was studied for 4 yr in four commercial groves in coastal southern California. There were two treatments in each grove: treated plots where bud mite was suppressed with acaricide treatments whenever infestation levels increased markedly, and untreated plots where bud mite was not controlled. Average percentage of axillary buds infested with citrus bud mite was 7-15% in treated plots and 45-70% in untreated plots over the 4-yr period. Citrus bud mite feeding results in distortion of fruit shape which can result in commercial downgrading. Citrus bud mite control significantly reduced fruit distortion in all four groves and significantly improved commercial packout in three of the four groves. However, significantly less distortion in fruit was not detected in treated trees until harvests ≥10-13 mo after the initial acaricide treatment (lemons in coastal California are harvested three or four times per year). This supports the hypothesis that distortion in fruit is caused by citrus bud mite feeding on embryonic fruit tissue in the buds; once fruit set, they are unaffected by further citrus bud mite feeding. Up to 21 mo after the first acaricide treatments, the cumulative yield did not differ significantly between treated and untreated plots. In two of the four groves, in the eight harvests between 24 and 48 mo after the first acaricide treatments, the cumulative yield was often significantly greater (9-13% greater) from treated than from untreated trees. The other two groves showed no significant differences in cumulative yield between treated and untreated trees up to the time of the last harvest (28 and 49 mo after the first acaricide treatment). In two groves, economic loss justified the cost of bud mite suppression, and in two groves, the cost of suppression exceeded the economic benefit of suppression.
and Emer gency Project established a statewide monitoring program to determine the extent of the ... more and Emer gency Project established a statewide monitoring program to determine the extent of the olive fruit fl y's occur rence, track its seasonal biology and evaluate monitoring tools. Fly popu lations and infestations can reach high levels throughout California but tend to be lower in the San Joaquin Valley. Trap captures typically exhibit a bimodal distribution with peaks in the spring and fall. Olive infestation is related to fl y densities, climate and fruit size. Gravid, mated females vary in density throughout the year but are present at some level yearround. The data is being used to develop models that will better predict when the adults are active and olives are at risk.
... large necrotic areas but &gt;50% ofthe bud remains suc-culent and undamaged; 3, moderate ... more ... large necrotic areas but &gt;50% ofthe bud remains suc-culent and undamaged; 3, moderate to severe damage, necrotic areas extensive, &lt;25% of the bud is still succulent and healthy; 4, severe dam-age, outer bud scales are all dark, hard and dry, no green succulent tissue left ...
Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in ou... more Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in our understanding of this pest. We now know the area of origin of the avocado thrips and have compiled an inventory of other potential pest thrips species on avocados in Mexico and Central America. Trials have helped us to identify several selective insecticides for use in treating avocado thrips in orchards. We have also determined the relationship between thrips densities on leaves and fruit scarring, and are studying cultural and biological control practices for use in an evolving integrated pest management (IPM) program.
Use of abamectin for avocado thrips, Scirtothrips perseae, also has effects on the persea mite, O... more Use of abamectin for avocado thrips, Scirtothrips perseae, also has effects on the persea mite, Oligonychus perseae, and avocado bud mite, Tegolophus myersi, in Ventura County, California. In this study individual trees were treated with the standard insecticides for thrips, sabadilla (Veratran D) and abamectin (Agri-Mek), using a backpack sprayer, or left untreated. Sabadilla reduced S. perseae numbers on young and old leaves but failed to reduce O. perseae and T. myersi numbers. Abamectin significantly reduced numbers of all three pests. In addition, abamectin reduced the amount of leaf drop associated with O. perseae feeding. In a companion trial, where abamectin and sabadilla were applied by ground rig in one orchard and another orchard was left untreated, there were no differences in T. myersi populations. When all three pests are present, the use of abamectin may be a more efficient strategy than the use of sabadilla.
Scirtothrips perseae Nakahara was discovered attacking avocados in California,USA, in 1996. Host ... more Scirtothrips perseae Nakahara was discovered attacking avocados in California,USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a ‘‘classical’’ biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (\u3e1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (\u3e1300 m)....
Pruning as a cultural practice has been increasingly used in Southern California avocado orchards... more Pruning as a cultural practice has been increasingly used in Southern California avocado orchards. This practice promotes the production of flush growth, which is the preferred food source of avocado thrips (Scirtothrips perseae Nakahara). Currently, most pruning activities take place in January, February or March. To determine when pruning ‘Hass ’ avocado least affects fruit set and minimizes avocado fruit relates monthly pruning times in 2002 to the presence of flushing leaves as a food source for avocado thrips, the numbers of immature avocado thrips, and to the 2002 and 2003 fruit set. Pruning between January and May promoted the prolonged presence of flush during fruit set and early fruit development through August and delayed the hardening of the leaves. With the grower's IPM program, which used 4 chemical treatments to suppress avocado thrips, the number of thrips was significantly higher on trees pruned
Project history These studies are also known as (a part of) BIOSA, a project aiming to develop a ... more Project history These studies are also known as (a part of) BIOSA, a project aiming to develop a “Biologically Intensive Orchard System for Avocado ” which would ultimately integrate non-chemical pest control methods and cultural management into a suggested method for growing avocado with fewer pesticides. Pruning, mulching, planting several plant species on the orchard floors, different means of fertilization and release of potential natural enemy (NE) agents for biological control were planned for subsequent years after establishing the current practices for managing avocado thrips problems and identifying the species and numbers that make up the resident natural enemy populations in avocado groves. Time restrictions and limitations of manpower have resulted in this 2-year survey of avocado thrips and their potential natural enemies in 2003 and 2004, with correlations of natural enemies with distance from the coastline and fraction of orchard floor covered with leaf duff, living o...
aged by crows. From these estimates, we calculated a 3 to 4% loss in production, about 40 pounds ... more aged by crows. From these estimates, we calculated a 3 to 4% loss in production, about 40 pounds per acre, for those returning the survey. In estimating overall loss, average losses in the range of 1 to 5% and 6 to 10% were reported by 28% and 26% of the growers, respectively; 24% of the growers indicated losses in the range of 11 to 50%.
The vineyard training/pruning system can dramatically influence the amount of Botrytis bunch rot.... more The vineyard training/pruning system can dramatically influence the amount of Botrytis bunch rot. Trying to achieve better light reception can impede air movement and result in &eater incidence of rot. Researchers recently concluded that growers can manage a vine's microclimate to reduce the development of Botrytis bunch rot in vineyards by increasing the air movement around clusters. Differences in Botrytis severity were further noted during a study of different trellis heights and different training and pruning methods in a Santa Maria white riesling vineyard. Previous data had focused on vine yield and fruit composition parameters. In 1985 the study was expanded toincludetheincidence of Botrytis bunch rot among the differently established vines. Insufficient air circulation can promote Botrytis bunch rot in grapes. Proper pruning keeps the fruit bunches clear of enveloping leaves.
... continuously agttated until essentially all the mixture was incorporated in or on the twine. ... more ... continuously agttated until essentially all the mixture was incorporated in or on the twine. Another formulation, which we call "ant tape," was prepared in the followingway. <?neto three strands of cotton twine, permeated Withrepellent ...
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