Evaluation of fungicides for purple blotch control on onion, 2006

摘要

Fungicides were evaluated on onions grown on Hidalgo fine sandy loam soil. Treatments were replicated four times in a randomized complete block design. Each plot consisted of two beds, 20-ft long and 40-in wide. Adjacent plots were separatedby two untreated beds. Prefar 4E at 1.5 gal/A was over sprayed on plots on 1 Dec 05 for weed control. Onion plants were transplanted into two rows on each bed with 3-in spacing between plants on 5 Dec 04. Nitrogen was applied to plots in 10 lb/AN32%, 12 Dec 05 and 9 Jan and 20 lb/A N32% treatments on 23 Jan and 17, 23 Feb and 2 Mar 06 respectively. Plots were watered with drip irrigation. Onion and western flower thrips were controlled by applications of Assail 70WP 1.7 oz/A on 2, 19 Jan and 17Feb and Lannate LV at 3.0 pt/A on 10 Jan and 26 Jan and Warrior T 1CS at 3.2 fl oz/A on 15 Jan and 10, 28 Mar and 5 Apr. Fungicides were dispersed in water and applied at the rate of 55-gal/A through five hollow cone nozzles (25 core and D2 tip) per bed under 80 psi. Fungicides were applied six times on 7-10 day schedule beginning 20 Feb. Disease ratings were made on 12 Apr and bulbs were harvested on 24, 25, 26, 27, 28 Apr and graded according to size. Average monthly temperatures were normal, ranging from 64.3F in Jan and 80.3F in May. Rainfall was below normal, ranging from 0.08-in. in Jan to 1.36-in. in May.