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The effects of johnsongrass [Sorghum halepense(L.) Pers. # SORHA] infestations were determined during a 2-yr study on sugarcane (Saccharum officinarumL. ‘CP-65-357’) yield. Both cane and sugar yields were lower (36 and 31%, respectively) in plots heavily infested with johnsongrass than in weed-free plots. Sugarcane yields were inversely influenced by johnsongrass equivalents (the sum of the values obtained by multiplying the number of clumps by their corresponding importance value for each plot). In 1983, both johnsongrass standing crop and johnsongrass equivalents correlated negatively with cane yield much better than any other factor combinations, while in 1984, the same was true for stalk population. Substantial yield reductions from johnsongrass interference were observed at johnsongrass infestation levels higher than 15 to 35%.

No abstract

Acaricides were compared for efficacy in reducing numbers of mites and mite eggs on field roses. Plots were sampled on 1 Jun, 3 days prior to treatment; pretreatment counts did not significantly differ. Treatments were applied with a CO2 backpack sprayer at 100 psi with hollow cone nozzles. The Avid treatment at 400 gpa was applied with a Solo knapsack sprayer at 32 psi. Treatment design was a RCB with 8 replications. Each plot was 20 ft of row of two adjacent rows (42 inch row spacing) with a 5 ft buffer between plots in the row. Plots were bordered by untreated rows of roses. Twenty leaves per plot were taken at weekly intervals, transported to the lab, brushed onto glass plates, and counted in concentric fashion using a template. Data are the mean of replicates, and represent the mites counted on one-sixth of the plate. Data were (x + 1) transformed to establish homogeneity of variance. Means shown were obtained by back-transforming the data. No phytotoxicity was observed.

No abstract