Effect of colored shade nets on pepper powdery mildew (<Emphasis Type="Italic">Leveillula taurica</Emphasis>) |
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Authors: | Yigal Elad Yoel Messika Michal Brand Dalia Rav David Abraham Sztejnberg |
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Institution: | (1) Dept. of Plant Pathology and Weed Research, ARO, The Volcani Center, 50250 Bet Dagan;(2) Dept. of Plant Pathology and Microbiology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, 76100 Rehovot;(3) Extension Service, Israel Ministry of Agriculture and Rural Development, 85410 Gilat, Israel |
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Abstract: | The effect of colored shade nets with different shade intensities and qualities of irradiation transmittance on pepper powdery
mildew was tested in mini-plots and field experiments. Leaf coverage byLeveillula taurica and leaf shedding due to the disease were more severe in the shade, by up to 275% and 70%, respectively, than in the open
field. Leaf coverage byL. taurica symptoms and leaf shedding from plants grown under 25% shade black nets were higher, by up to 70% and 180%, respectively,
than under 40% shade nets. The color of the shade nets affected the intensity of photosynthetically active (PAR), ultra-violet
(UV), blue, red and far red radiations, the UV/blue light ratio, and percent PAR and UV transmitted. The various nets suppressed
the disease differently. Black, blue-silver, green and red nets were associated with lower levels of disease in the field
experiments. The red net was also superior in the mini-plots. The other results from the mini-plots were not similar to those
from the field, probably reflecting more intensive epidemic development in the mini-plots. No interaction between net type
and cultivar was found when two cultivars were grown under the nets. Yield was higher under nets than in the open; nevertheless,
the yield from plants grown under the 40% shade black net was not higher than that of the plants under the 25% black net,
despite the significantly lower levels of disease at the higher shade intensity. B-quality pepper yield was significantly
higher in the plots covered by 25% shade. Yield differences between the different colored nets were also not well correlated
with disease levels, probably due to factors negating the direct effect of the nets on the plants and their yield. Implementation
of either ‘friendly’ (Ampelomyces quisqualis AQ10/Trichoderma harzianum T39/ sulfur/ neem seed extract) or chemical (sulfur/ pyrifenox/ Polyoxin AL/ myclobutanil/ azoxystrobin) spray regimes successfully
reduced disease severity under the different nets. There was no interaction between net type and spray regime. Thus, growing
sweet pepper under shade nets results in increased yields and also in higher powdery mildew severity. Disease is negatively
associated with the rate of shading and is variably affected by the quality of light filtered through the different colored
shade nets.
http://www.phytoparasitica.org posting May 8, 2007. |
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Keywords: | Alternation biocontrol agent biological control Capsicum integration selective light filtration sweet pepper |
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