Influence of Planting Date, and Early-Season Soil and Weather Variables on Severity of Race 4 Fusarium Impacts on Cotton

Field studies have been conducted that included different planting dates for a limited selection of Pima and Upland cotton cultivars in fields confirmed to be infested with race 4 Fusarium oxysporum f. spp. vas infectum (FOV-4).   In these fields, soil temperatures were monitored at multiple depths, soil water content at planting timing was determined, and weather conditions during the period from planting to the 2nd fully expanded leaf stage were monitored, with the goal of being able to describe general conditions of soil temperature, beginning soil moisture, and air temperatures associated with a range of planting dates.  Plants were evaluated at the timing of 4-5 weeks post planting to assess plant survival percentage of emerged plants, and root vascular stain ratings as an indicator of infection with FOV-4.  Plants were seeded into and grown in containers in the greenhouse that received a known volume of solution containing an FOV-4 conidial suspension to assess if there were significant impact of soils differing in pH and salinity on plant survival and severity of root vascular staining.  Results will be discussed in relation to incidence of other seedling diseases observed in field planting date studies, and potential soil pH or EC impacts on severity of plant losses or infection rates in field FOV-4 screening sites.