No description available.

Aflatoxin contamination of cottonseed from bolls damaged by the pink bollworm was compared with contamination of cottonseed from undamaged bolls. Cottonseed produced in pink bollworm damaged bolls was the predominant source of aflatoxin contaminated cottonseed.

Methyl bromid/chloropicrin, a soil sterilant, was deep injected into cotton beds 10 days before planting in 1987. The 1987 cotton lint yields were significantly increased by injecting the sterilant into the Texas root rot kill areas. Cotton yield and mortality data were taken in the same plots in 1988 to measure the carry-over of the treatments. Lint yields trended higher and plant mortality trended lower in the sterilant- treated plots, but no significant differences were detected.

Methyl bromide/chloropicrin (MB/C), a soil sterilant, was deep injected into cotton beds 6 days before planting in 1988. Application rates were zero, 300, 400, and 500 pounds of MB/C per acre, injected 18-inches deep into the sandy loam soil. Short staple lint yields in all of the MB/C treatments were significantly higher than the untreated check. MB/C at all application rates was 100% effective in preventing the plants from dying from the disease, while 86% of the plants in the untreated check plots died.

The loss of dying pima cotton after a rainfall in August 1987 made apparent the different responses pima and upland cottons have to stress. A trial compairing pima S-5 and DP 77 found more response of pima to treatment of rootknot nematodes with 1,3-Dichloropropene than the upland variety. A second trial found more response of DP 77 to 1,3-Dichloropropene treatment than from fenamiphos injection on sandy loam.

No description available.

Studies were conducted in Phoenix AZ, to determine the development of boll weevil, Anthonomus grandis Boheman, infestations in late - season cotton bolls, the pattern of boll weevil emergence, and survival /mortality in the bolls. Boll weevils emerged from bolls buried in moist vermiculite over a period of 232 to 239 days, from 29 January to 2 August. Higher percentages of emergence and lowest mortality in bolls occurred in bolls collected in November as compared to bolls collected in December. Few boll weevils emerged from bolls held under dry conditions in an outdoor insectary for 174 days. However, an average of 16% of the weevils were found alive in the dry bolls in late May.

An experimental cotton line, WC-12NL (nectariless, okra leaf early maturing) was compared in large plot (2-acre) replicated experiments with a standard cultivar, 'Deltapine 61' ( nectaried, regular leaf shape, full-season), for 3 seasons, 1986 to 1984 at 2 locations, Maricopa, AZ and Brawley, CA. Ethephon ("Prep") was applied to half of each plot when the crop was ca. 60% open. Pink bollworm (PBW) eggs were counted twice weekly on bolls and the 2 cottons were sprayed separately for PBW control when the egg infestation on bolls reached the action level. Seed cotton was harvested weekly as soon as bolls started to open. Over the 3 seasons and 2 locations, WC 12NL yielded 12% more total lint, 43% more cumulative lint at the third harvest date, and required only 59% as much insecticide to control PBW as did Deltapine 61.

A single field experiment was conducted in 1989 on a grower cooperator field to evaluate the response of a medium maturity type Upland cotton (DPL-50) to three dates of irrigation termination. The crop was planted 20 April and managed uniformly in all respects until 2 August when the earliest irrigation termination treatment was imposed. The dates of the second and final irrigation terminations were 17 August and 1 September, respectively. With each subsequent irrigation, the respective plots received an additional six acre inches of water (approximately). Harvest results revealed no significant (P <0.05) differences in lint yield due to irrigation termination treatments. Overall mean lint yield for the experiment was 1,228 lbs. cotton lint/acre, the experimental coefficient of variation (CV) was 11% and the observed significance level (OSL) was 0.34.

A field study was conducted at the Maricopa Agricultural Center to evaluate the effectiveness of selected defoliation treatments on Pima cotton under warm and cool weather conditions. Dropp and other defoliants caused desiccation and freezing of leaves when applied at air temperatures above 100° F. Dropp was an effective defoliant when maximum air temperatures were in the low 90s. The experimental defoliant SN 597 NA218 appears to be a promising defoliant for Pima cotton when temperatures are cool.