Abstract
A two-year field trial was conducted in a vineyard (northern Egypt)cultivated with Thompson seedless grapevines to evaluate the effectiveness of four “alternative” (biological/chemical) treatments, Bacillus megaterium, boric acid, calcium nitrate and chitosan, against the root-knot nematode Meloidogyne incognita (Mi), compared to that of the nematicide oxamyl. The influence of these treatments on plant nutritional status and fruit yield and quality was also assessed. All treatments significantly inhibited Mi reproduction parameters in both seasons, decreasing the numbers of nematode galls and egg masses (roots) and of second-stage juveniles (soil). Oxamyl application resulted in the highest reductions in Mi-reproduction parameters, followed by boric acid, which also showed the highest relative nematicidal efficacy (respect to oxamyl). In the 1st season, the highest fruit yield (10.34 kg/grapevine) was recorded from boric acid-treated plants, followed by that from oxamyl-treated plants (7.50 kg/grapevine); in the subsequent season (2019), oxamyl use led to the highest yield, followed by boric acid + chitosan use (10.04 and 8.62 kg/grapevine, respectively). In both seasons, application of boric acid alone and combined with chitosan enhanced the total soluble solids (TSS)/total acidity ratio in grape juice. All treatments led to higher nutrient contents (leaf petioles) and chlorophyll levels (leaves) as well as enhanced fruit size and weight. We conclude that the tested treatments can be safely applied for nematode management in Thompson seedless grapevines, with positive effects on fruit yield and quality.
Highlights
Grape (Vitis vinifera L.) is one of the most important commercial fruit crops in the world and the first major deciduous fruit crop in Egypt, ranking in the second position after citrus
Over both experimental seasons (2018 and 2019), all treatments significantly reduced the numbers of nematode galls and egg masses/g fresh root, as well as the numbers of second
Regarding grapevine reproductive performance and yield, our results show that high values were achieved in both seasons when boric acid, alone or in combination with chitosan, was applied
Summary
Grape (Vitis vinifera L.) is one of the most important commercial fruit crops in the world and the first major deciduous fruit crop in Egypt, ranking in the second position after citrus. Nutritional status and productivity of Thompson seedless grapevines total grape-planted area has increased in the last years in Egypt, especially in newly reclaimed lands, covering about 827373ha. Most of this area is already fruitful, accounting for a total production of 1,686,706 tons, based on the latest Agriculture Statistics published by the Egyptian Ministry of Agriculture [1]. PPNs have expanded widely in the Egyptian vineyard soils [4] Their feeding habit on grapevine roots impairs water and nutrients uptake as well as root and shoot growth, resulting in reduced vine vigor and yield losses [5, 6]. There are many PPN species attacking grapevines throughout the world, not all species cause significant economic damage [9]
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