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Goal. Determine the damage to modern corn hybrids by the caterpillars of the cotton bollworm, develop a point scale for assessing the damage of kernels on the cob, and calculate the direct losses of grain yield. Methods. Field. The studies were carried in the research fields of the Cherkasy Research Station of Bioresources of the NSC «Institute of Agriculture of NAAS» 2017—2019. The cultivation of corn was carried out in accordance with the cultivation technology recommended for the Forest-Steppe zone of Ukraine, Cherkasy region. Plot size — 56 m2, in four replicates. Placement of plots — randomized. The number of damaged corncobs of cotton scoop was determined per hectare. To calculate the number of damaged kernels per corncobs, each damaged corn cobs was opened and the number of eaten and damaged kernels was counted. To calculate the direct yield losses for each corn hybrid, the total number of kernels eaten and damaged by the caterpillars of the cotton bollworm (per hectare) was calculated, which was multiplied by the mass of 100 kernels, respectively. Results. The degree of harmfulness of cotton bollworm caterpillars on maize hybrids of different maturity was investigated. In 2017—2019 The corncobs are most damaged in hybrids of the mid-maturing group — 58.4%, less — in early-maturing hybrids — 41.1%, and in the middle-early ones — 47.8%. For the first time, a nine-point scale was developed for assessing the defeat of caryopses on the cob by Helicoverpa armigera Hbn. caterpillars direct losses of grain yield are calculated. It was found that significant yield losses were observed in all mid-season maize hybrids (0.185—0.280 t/ha). Conclusions. In the Left-Bank Forest-Steppe of Ukraine, the cotton bollworm turned out to be a dangerous pest of the generative organs of corn. Therefore, the selection of resistant hybrids to attack by caterpillars of the cotton bollworm is a key element in the protection of this crop. And the nine-point scale developed by us allows us to assess the degree of damage to caryopses by the caterpillars of Helicoverpa armigera Hbn. |
