No abstract

Three different release rates and timings of the phytoseiid Neoseiulus californicus (McGregor) were evaluated for Oligonychus perseae Tuttle, Baker, and Abbatiello control on avocado trees in a commercial orchard in southern California, USA. Densities of natural enemies and O. perseae were monitored on trees for 34 weeks that were treated with either one, two, or three releases of 500, 1000, or 2000 N. californicus, or two applications of 5% narrow range (NR) 415 petroleum oil. Predator releases were made when 50% (release one), 75% (release two), or 95% (release three) of sampled leaves were infested with one or more motile O. perseae. Densities of O. perseae on trees treated with N. californicus or petroleum oil were compared to control trees that received no treatments for O. perseae suppression. Release of a minimum of 2000 N. californicus per tree was necessary to significantly reduce O. perseae densities in comparison to control trees. Releasing 1000 N. californicus twice or 2000 N. caIifornicus once provided O. perseae control similar to petroleum oil treatments and to trees treated with cumulative releases totaling more than 2000 predators per tree. This result indicated that releases totaling more than 2000 N. californicus per tree did not substantially improve O. perseae control and the cumulative number of predators released per tree is more important than the number of times N. californicus is released for controlling O. perseae.

The effect of abamectin on the leafminer, Liromyza trifolii (Burgess), was investigated using topical applications, leaf dips, and repellency bioassays. Topical application of technical material in acetone to susceptible adult females provides an LD50 value of 0.404 ppm. Leaf-dip assays using abamectin formulated in water with third-instar larvae gave an LC50 value of 0.386 ppm. These data provide baseline information on the toxicity of this material to L. trifolii and are important in the development of resistance management programs. Adult female leaf miners were repelled from feeding and ovipositing on chrysanthemum plants treated with formulated abamectin up to 7 days after foliar application in choice and no-choice assays. The implications of these data in managing populations of L. trifolii are discussed.

Phytotoxicity trials on bedding plants, Los Angeles, Co., CA, evaluated the effects of 1X, 2X and 4X rates of Avid 0.15E (0.01 lb (AI)/acre), Broot 50W, Dimilin 25W, Zolone 3E, and Evisect 50SP (1X = 0.5 lb (AI)/100 gal). One flat, containing 9 pony paks with 6 plants, was evaluated per treatment rate for each species. The materials were applied to runoff with a 2.5 gpm piston pump hand sprayer at 180 psi on 15 Jul (temp = 25-28°C). Phytotoxicity readings were compared to a water check 22 and 29 Jul.

Thirteen weekly applications of Evisect 50SP or Ekalux 480E at 0.5, 1.0 and 2.0 lb (AI)/100 gal were compared to 13 weekly applications of Trigard at 0.125 lb (AI)/acre. The materials were applied to 27 cultivars of chrysanthemums grown under commercial conditions without cover by the cooperating grower (San Luis Rey, CA). The plants were planted 6 Aug; treatments were initiated 13 Aug and ended 5 Nov. Six plants of each variety were planted in each of 7 rows, with 1 pesticide treatment per row. The materials were applied with a 15L backpack sprayer.