干旱区生态环境知识资源中心

Bermudagrass seed yields were significantly increased by use of insecticides which controlled Trigonotylus tenuis (Reuter) (Hemiptera: Miridae) and Chirothrips spp. (Thysanoptera: Thripidae), although use of methyl-ethyl parathion reduced yields. Seed yield differences among insecticide treatments which controlled thrips (other than methyl-ethyl parathion) were highly correlated with adult T. tenuis numbers on last sampling date (14 days) prior to harvest, which reduced seed yield by 22.1 kg/ha (19.7 Ibs/acre) per mirid/sweep. High numbers of T. tenuis were also highly correlated with reduced numbers of floral spikes, floral spike height and blade height early in crop development. Cypermethrin was not as effective as other insecticides in controlling T. tenuis but did control Toya propinqua (Fieber) (Homoptera: Delphacidae). Toya propinqua levels below 12.8/sweep did not cause sticky seed, and should be considered in future integrated pest management decisions. Increased seed production offset insecticide cost except for the methyl-ethyl parathion treatment. Insecticide cost coupled with value of hay loss due to non-feeding restrictions with certain insecticides is calculated to be uneconomical in fields with yield potential less than 785.3 kg/ha (700 Ibs/acre) or when hay price is high. Changing insecticide use patterns and controlling T. tenuis could result in potential yield increases of 298.7 kg/ha (266.3 Ibs/acre), valued at over $2.0 million per year to bermudagrass seed industry.