Bean thrips- Are field treatments feasible?
Grafton-Cardwell and Morse have held off suggesting that growers should spray citrus groves in the fall to control bean thrips. There are several reasons for this: (1) to date, bean thrips has been a problem mainly for shipments of navel oranges to Australia and New Zealand and it is difficult to know which fruit will be destined for this market, (2) levels and timing of bean thrips flying into citrus in the fall can vary greatly from year to year (depends a lot on when weed hosts and other plants dry up, when the weather turns cold, etc.; some years, bean thrips move in early and feed on the fall flush, other years this movement is later), (3) bean thrips typically fly into citrus over a 3-6 week period and it would be difficult to maintain an effective pesticide residue on citrus without multiple applications, (4) once the bean thrips are inside the navel of navel oranges, they are difficult to control, and (5) we are looking forward to the registration of ethyl formate as a post-harvest treatment (hopefully in time for the 2013-14 shipping season). An effective post-harvest treatment would be a much more practical means of dealing with this problem than field sprays - only loads of packed citrus destined for AU/NZ would be treated.