Fungus Report - 2001 Crops Day

Eric Eriksmoen - Agronomist

Rick Olson - Technician

Lance Ketterling - Cooperator

Dwelley chickpea was seeded on May 4. Seed was inoculated with rhizobia and treated with LSP and Apron prior to seeding. 50 lbs/acre 11-52-0 plus 10 lbs/acre ‘Roughrider’ (3 lbs/ac copper) fertilizer were applied with the seed. The first treatment application was on July 2 to chickpeas in early bloom. The second treatment application was on July 16 to chickpeas in late bloom. A third treatment application was applied on July 30 to chickpeas that were completely podded and developing peas. Treatments were applied with a tractor mounted CO2 propelled plot sprayer delivering 17 gpa at 40psi through 8001 flat fan nozzles to a 5 foot wide area the length of 10 by 28 foot plots. The experiment was a randomized complete block design with four replications. Visual evaluations for ascochyta infection on crop leaves and pods were on July 13, July 23, July 30, August 6 and on August 13. The trial was harvested on September 6. Harvested seed was cleaned with a clipper mill to remove chaff and weed seeds and then graded according to seed size.

Weather conditions were ideal for ascochyta development during the month of July with 15 days of measurable precipitation totaling almost 4 ½ inches of rain. Hot and dry August weather conditions ceased the progression of ascochyta with only 2 days of measurable precipitation totaling 0.13 inches. Evaluations on July 13 showed minor levels of visual ascochyta on all treatments (data not shown). Split applications of BAS 500, BAS 516 and Quadris (trts 4 - 9) provided good season long control of ascochyta, had the highest seed yields, the highest test weights and the highest % of large seed. Split applications of Bravo WeatherStik and Bravo Zn (trts 20 & 21) also provided relatively good seed yields. The single early application of BAS 500 (trts 2 & 3) provided good initial ascochyta control but deteriorated as the season progressed. Seed yield, test weight, seed weight and % large seed from these two treatments were still significantly higher than the untreated check. The second application of BAS 500 (trts 4 & 5) significantly enhanced ascochyta control and seed yields over the single BAS 500 application (trts 2 & 3). Split applications of Bravo Ultrex and Topsin M were not effective in controlling ascochyta. The addition of Scalia to the Bravo Ultrex/Topsin M mixture (trts 12 & 24) did not significantly enhance ascochyta control or seed yield over the single product mixture (trts 10 & 13). Higher fungicide application rates did not significantly enhance ascochyta control or seed yields (trt 3 vs.2, trt 5 vs.4, trt 7 vs.9).

*Ascochyta Rating (0-9): 0 = no visual ascochyta on leaves or pods, 9 = dead plants