Elkner, T.¹ and S. J. Fleischer^2
1Penn State Cooperative Extension, 1383 Arcadia Rd., Rm. 140, Lancaster, PA 17601
²Dept. of Entomology, Penn State University

Abstract. Production of sweet onions for the PA Simply Sweet® Program is a newer option for growers seeking to diversify their farming operation. Control of onion thrips, the main insect pest on this crop, is a concern because of resistance issues. Two varieties of onion were planted on three mulch colors; after thrips populations developed half of each plot was sprayed with spinosad. Counts of thrips per leaf were highest on white mulch on two separate counts prior to spinosad application. There was no difference between black and silver on the first count while silver was lower than black on the second. Visual damage was lowest on silver mulch for both counts; black was not different than white on the first count but was lower on the second. After spinosad treatment there were no differences in thrips populations between mulches. Onions grown on silver mulch had the highest soluble solids while those grown on black were lowest. Onions grown on white plastic had intermediate values and were not different from those grown on black or silver mulch. There was no effect of mulch color on average bulb size. “Expression” had higher numbers of thrips per leaf on the first count but was not different from “Candy” for other measurements. Spinosad application reduced thrips populations and damage rating on the post- spray rating but did not affect soluble solids or average bulb weight.

There is no full paper associated with this abstract.