Justification and Problem Statement
The western tarnished plant bug is a key pest of cotton in western arid production regions. Populations of lygus bugs are difficult to monitor because adults are active fliers, and nymphs inhabit cryptic habitats and move rapidly when disturbed. Management decisions are complicated by these difficulties. Because the principal management tactic for lygus bugs is chemical pesticides, treatment decisions based on inaccurate sampling data may result in either unnecessary crop loss, or unneeded pesticide applications that my contaminate the environment and induce secondary pests. Considerable effort has been devoted in cotton production regions of the West and Mid-South to evaluate and improve sampling methodology for lygus bugs. However, in recent efforts the criteria for the selection of sampling methods have focused on maximum numbers of bugs collected or apparent precision of population estimates without consideration for the fidelity of those estimates to actual bug populations. Development of efficient and practical absolute or near-absolute sampling methods for one or more stage of lygus would allow more meaningful evaluation and perhaps calibration…
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Objectives: To improve cotton germplasm with potential heat stress tolerance, better fiber quality, lint yield and pest resistance, broadening the genetic base of cotton.
Justification and Problem Statement
Over the last 3 5 years, the cotton germplasm base used in plant breeding has narrowed. This relatively narrow genetic diversity has been suggested as a contributor to an apparent plateau in breeding progress. It may also represent an impediment to efforts to sustain high yields (May and Taylor, 1998; Meredith, 1992; Ulloa, 2006). Since the re-establishment of a cotton breeding effort within the USDA-ARS, Western Integrated Cropping Systems Research Unit, we have focused on increasing genetic diversity through acquisition of novel germplasm (from multiple sources including non-commercial land races and species of wild cottons)…
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Greenhouse studies have evaluated the impact of metam sodium applications, with and without solarization films and associated soil heating, on development of FOV symptoms in varieties of cotton previously recognized as highly-susceptible (a Pima, Phytogen 810-R or DP-744) or moderately susceptible (an Acala, Phytogen-72). The soil media used was a 1:2 mix of soil from a highly infested field site mixed with steam-treated potting mix. Trays of soil mix received the treatments and post-treatment, the soil was transferred into clean, waxed cardboard containers to plant out the seed for further evaluations of disease symptom development and plant survival percentages. In metam sodium trials, three different rates of metam sodium alone did not significantly impact the survival rate (about 30%) or symptoms (root vascular stain index rating averaging about 3 on a scale of 0 (no symptoms) to 5 (severe symptoms) in highlysusceptible Pima varieties. In the moderately susceptible Acala variety, the metam sodium treatments improved the survival rate and reduced vascular stain ratings wl1en compared with untreated soil. In the first trial, averages of about 90% survival were recorded for treated soil versus about 60% survival for untreated. In the second trial, an average of about 90% survival was recorded for treated soil versus…
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Changes in the California cotton industry enacted in 1998 allow for a much broader range of varieties to be grown in the SJV. It will be important for growers to have unbiased sources of varietal performance information that will answer some of the questions regarding yield performance, growth characteristics and quality of available varieties. These trials involving newly-available CA Upland varieties complement the combined SJV Cotton Board and the UCCE Farm Advisor Approved Acala studies. Trials include standard varieties of Acalas in order to have some more complete indices of varietal comparisons. The range of yield potential as well as the range of quality characteristics across the varieties now available will mean that growers have an even more difficult job than usual in balancing the combination of yield and quality (and resulting price)…
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Justification and Problem Statement
The western tarnished plant bug is a key pest of cotton in western arid production regions Populations of lygus bugs are difficult to monitor because adults are active fliers, and nymphs inhabit cryptic habitats and move rapidly when disturbed. Management decisions are complicated by these difficulties. Because the principal management tactic for lygus bugs is chemical pesticides, treatment decisions based on inaccurate sampling data may result in either unnecessary crop loss, or unneeded pesticide applications that my contaminate the environment and induce secondary pests. Considerable effort has been devoted in cotton production regions of the West and Mid-South to evaluate and improve sampling methodology for lygus bugs. However, in recent efforts the criteria for the selection of sampling methods have focused on maximum numbers of bugs collected or apparent…
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Summary:
Cotton is routinely grown in the hot, irrigated areas of the far Western U.S., and these extended periods of high temperature can reduce cotton ( Gossypium hirsutum L. and G. barbadense) lint yield, even with adequate irrigation conditions. Extended periods of extremely high temperatures are common in these areas during the critical stage of peak flowering. When temperatures in the San Joaquin Valley reach temperatures above normal during the critical stage of peak flowering, California growers suffer the consequences of reduced yield by these cotton varieties weaknesses to heat. The number of cotton commercial varieties for California with heat tolerance is not really known. However, it is known that Acala varieties Maxxa and Phytogen 72 yield poorly in the heat stress environment of…
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Summary:
Since the re-establishment of the USDA-ARS, WICS, genetic/breeding program, we have been focusing on bringing germplasm from any possible source available to us in order to increase genetic diversity. Most of the time, the genetic diversity in the cotton crop is used as an indicator to recognize potential threats to sustaining high yields. In the last couple of years, several troubling developments have recognized Fusarium oxysporum f.sp. vasirifectum (FOV) Atk. Sny & Hans as a recurring and potentially expanding threat to cotton production. The vulnerability of cotton production to this pathogen highlights the need for comprehensive research to protect the cotton industry from FOV, both from virulent populations which may be introduced and new virulent strains arising from within cotton production areas. Until recently, only race 1 and race 2 were known to occur in the United States (DeVay, 1986; Smith et al., 1981). UC scientists have recently identified race 4 ofFOV in cotton plants…
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Justification and Problem Statement
The Western tarnished plant bug, Lygus hesperus is a major pest of cotton in the San Joaquin Valley and a closely related species, L. lineolaris, is quickly becoming the primary pest of cotton in the Southeast US. Research in the past few years aimed at developing a control strategy that targets the pest species and sustains natural enemy populations, which would otherwise be killed by chemical pesticides that are currently used. Beauveria bassiana is a fungal pathogen that infects a wide range of insect hosts including Lygus bugs. Commercial formulations of this fungus are…
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