2. Frit‑fly problems.

The final analysis of our frit‑fly data has shown that all varieties of sweet corn are susceptible to damage, some varieties and hybrids more than others. There is a possible genetical basis as some American breeders have produced less susceptible types than others. Susceptibility is not associated with the suitability of varieties to English conditions nor to their maturity rating. It has been found that sowing sweet corn at different dates influences the severity of attacks and peaks vary according to variety and fram year to year. Later sowings seem preferable. Frit‑flies attack a crop of any one variety at random but there is a suggestion that plants in stringers radiating from a central mass are damaged more in the direction of the prevailing winds, but there is no regular decrease in incidence with distance from the central mass.