Injuriousness of raspberry cane midge and heat injury to remontant raspberries

Abstract

The authors found that in long-term studies, the levels of damage to raspberries of the remontant type of fruiting by raspberry gall midge Resseliella theobaldi (Barn.), associated with mycosis - midge blight: the development of the disease ranges from 29 to 40%. Also, deep necrotization of the internal tissues of the stem (loss of commercial productivity) ranges from 15 to 28% of the total number of shoots. Therefore, gallic burn with an average and severe degree of damage significantly affects the growth, development, and productivity of annual shoots of remontant raspberries. In addition, gall midge burn reduces the total number of internodes formed by 10–15%, increases the number of vegetative nodes on the shoot by 13–32%, and reduces the length of the productive shoot by 12–17 cm. In addition, the diameter of the generative projection at the base is reduced by 14%, the number of generative organs is reduced by 1.4–5.2 times, the weight of 1 fruit is also reduced by 1.1–1.4 times, the productivity of 1 shoot also decreases by 1.6–5.4 times. The authors found that the severity of gall burn on a remontant weakly resistant raspberry variety can theoretically be calculated by a regression equation for the relationship between the level of disease development (X) and the degree of decrease in shoot productivity (Y): Y = -0.6395 + 0.6267X + 0.0019X2, which allows interpolating estimates for any levels of damage to stands.