Soil Applied Systemic Insecticide for Leafhopper Control on Grapes, 1983

Abstract

Abstract The test was conducted in an established Concord grape vineyard in North East, Pa. Plots consisted of six vines in a row, replicated three times in a randomized complete block design. Vine spacing was 9 ft between rows and 8 ft within rows. Treatments were applied on 24 May when shoot length averaged 4.2 in. Equipment used was a Soil Serve granular applicator equipped with one drop tube positioned to discharge to a depth of 3 in. behind a single cultivator tooth, 1 ft from the trellis row. Each side of the trellis was treated. Furrows were covered by raking immediately following application. Soil type was a Wellington silt loam. Precipitation totalling 0.81 in. occurred during the week following application; precipitation in June (2.30 in.) and July (2.16 in.) was 0.7 to 0.8 in. below normal; precipitation in Aug. (3.19 in.) was normal and that for Sept. (4.95 in.) was about 1.25 in. above normal. Treatments were evaluated by counting the number of leafhopper nymphs on 10 injured leaves per plot at approximately 30, 60, 90, and 120 days posttreatment. The percentage of leaves injured was based on a 50-leaf sample per plot. Leaf injury severity was rated at harvest using a modified Horsfall - Barratt scheme: 0 = no injury, 1 = trace - 3% of leaf surface injured, 2=3 - 6%, 3=6 - 12%, 4 = 12 - 25%, 5 = 25 - 50%, and 6 = >50%; 50 leaves were rated at random per plot.