Codling moth proof hail nets
2008
Sauphanor, Benoit, | Severac, Gaetan | Romet, L. | Morel, Estelle | Toubon, J-Francois | Maugin, Sandrine
Single row hail nets (3x7.4mm) modified to wrap up whole tree canopies, named Alt’Carpo, were evaluated as a way of control of orchard lepidopteran pests. A two years study was conducted in a 10 rows experimental apple orchard in Southern France, together with large field trials in commercial orchards. The experimental orchard was insecticide free in year 1 and pesticide free in year 2. Eight rows were protected with the nets, two rows were unprotected. The nets allowed an 80% reduction of fruit injury when compared to the unprotected rows, which suffered over 70% codling moth injury. However this efficacy was lower than in commercial orchards, especially those covered with 2.2x5.4mm nets in which fruit injury did not exceed 0.1%. The outer females, issuing from unprotected rows, were proved able to lay eggs on leaves or apples touching the 3x7.4mm nets. Virgin females or synthetic lures baited traps poorly captured wild or marked and released males under the nets, while the traps placed in unprotected rows captured over 30% of the released males. Moreover, significant rates of males released under the nets were captured outside while only 1 out of 300 males released in the control rows was observed to pass through the net, proving the need for flying over the canopy for sex encounter. Despite the known alteration of communities in protected crops, no significant effect of the net was observed on rosy aphid and scab injuries on leaves or fruits. The agronomic, economic and environmental consequences of replacing chemical insecticides by synthetic barriers are discussed.
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