Abstract
Recurrent selection is being used to improve Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) resistance in Upland (Gossypium hirsutum L.) and Pima (G. barbadense L.) cotton using naturally infested fields and artificially inoculum-greenhouse sites. Our primary objective is to introduce a known FOV4 dominant gene that has shown resistance in Pima into the Upland species. In 2013, 2014 and 2015, we evaluated 1155 entries for resistance. These entries were exposed to FOV4 pressure in naturally infested fields and rated. Selected entries were then self- and cross pollinated. Parental lines and F1 populations were then inoculated with FOV4 and grown under greenhouse conditions for rating and reselection. This research will provide additional germplasm to broaden the genetic base for FOV4 resistant cotton.
Introduction
In California, Fusarium wilt of cotton is a serious fungal disease that is caused by Fusarium oxysporum f. sp. vasinfectum (FOV). Practices that have reduced the effects include not planting in sandy or sandy-loam textured soils that have a high infestation of root knot nematode and use crop rotation to help manage soil inoculum levels. This has been useful with FOV races 1 and 3, but Fusarium oxysporum f. sp. vasinfectum (FOV4) has been found to cause substantial damage in the absence of root knot nematode (Meloidogyne incognita) and persists even when crop rotation is practiced. Thus, the only long-term management of FOV4 is developing resistant cultivars. One objective of this study is to evaluate a known resistant FOV4 dominant gene from Pima (PS6) for potential introgression into Upland germplasm. The second objective is to identify and develop Upland germplasm…
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University of CA and USDA-ARS Fusarium Screen Summary – 2013 trials
Hutmacher, Wright, Ulloa et al – February 2014
Univ. California and USDA-ARS Fusarium-Race 4 Screenings (THREE SITES: Kern County and Tulare County sites plus greenhouse site at Kearney REC – 2013)
2013_Fusarium Race 4 Field Ratings SUMMARY TABLE – means and std deviations only
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Cotton Harvest Aid Management 2013
This report summarizes the applied defoliation research studies conducted during 2013. This was another unique season due to warm weather causing rapid progression of the cotton crop. Three research trials were conducted on Pima cotton at the Westside Research Center in Five Points, CA. These fields were planted with Phytogen 802RF on April 16, 2013 with a seed rate of 18 lbs/A. The fields received a pre-irrigation, three in-season irrigations, and pressure bomb readings were taken to better manage plant vigor. In addition, the fields received 140 lbs of nitrogen urea plus 14 lbs sidedress of Temik (Aldicarb) on May24, 2013. The fields also received 16 ounces of Mepex (Mepiquat Chloride) on June 19th and again on July 1, 2013. The plots were 65’ in length and consisted of four rows with 40” spacing. In each trial, each treatment had 4 replications.
The objective of these studies was to define the most appropriate conditions for effective defoliation and crop termination. New harvest aids and several tank mix combinations…
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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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PROJECT SUMMARY
In California, Fusarium wilt of cotton has been considered a potentially serious fungal disease caused by the organism Fusarium oxysporum vas infectum (also called “FOV”). However, in the past, damage associated with Fusarium in SJV cotton has been notable only in production areas with the combination of: (a) moderate to high populations of a specific race of FOV (usually race 1 ); (b) soils witl1 a sandy or sandy loam texture; and (c) root knot nematodes present in high-enough populations to cause significant galling and root damage. Past research generally indicated that FOV damage was worst when both FOV inoculum and nematodes were present in relatively higl1 concentrations. Methods used in the past to limit damage to cotton associated with Fusarium wilt have been to avoid planting cotton in soils in which the combination of sandy or sandy loam texture is combined with the presence of root knot nematode, or grow cotton only infrequently…
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Fusarium w.ilt of cotton in California has been considered a potentially serious fungal disease caused by the organism Fusarium oxysporum vas infectum (also called ”FOV”) for many decades in several areas of the San Joaquin Valley (SJV). In the past, however, damage associated with FOV in SJV cotton has been notable only in areas with the combination of: (a) moderate to high populations of one or more specific races of FOV (usually race 1 ); (b) soils with a sandy or sandy loam texture; and (c) where root lrnot nematodes were present in high-enough populations to cause some significant root damage. Past research generally indicated that FOV damage was worst when both FOV inoculum and nematodes were present in relatively high…
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Preventing sticky cotton is crucial in producing quality cotton. Late-season populations of cotton aphid and Silverleaf whitefly can produce significant amounts of honeydew when populations build. These pests are of most concern from mid-boll filling through harvest, when insect populations build and threaten exposed lint. Pest management guidelines for cotton aphid and silverleaf whitefly focus on strategies to use once threshold pest populations are reached, with the approach varying with the composition of the developing population (nymphs, adults), crop growth stage, and with the presence of exposed lint. Current pest management guidelines for whitefly and aphid can be interpreted as meaning defoliation is the final event of the season. This is based on the assumption…
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