ABSTRACT
High temperatures, wind, and excessive sunlight can negatively impact yield and fruit quality in semi-arid apple production regions. Netting was originally designed for hail protection, but it can modify the light spectrum and affect fruit quality. Here, pearl, blue, and red photoselective netting (≈20% shading factor) was installed in 2015 over a commercial "Cameron Select® Honeycrisp" orchard. Our research objectives were to (1) describe the light quantity and quality under the colored nets compared to an uncovered control and (2) investigate the effect of Photoselective nets on "Honeycrisp" apple quality for two growing seasons. Light transmittance and scattering for each treatment were measured with a spectroradiometer, and samples for fruit quality analyses were collected at harvest. PAR (photosynthetic active radiation), UV, blue, red, and far-red light were lower underneath all netting treatments compared to an uncovered control. The scattered light was higher under the pearl net compared to other colors, while red and far-red light were lower under the blue net. For two consecutive years, trees grown under the photoselective nets intercepted more incoming light than the uncovered trees with no differences among the three colors. In both years, trees under red and blue nets had more sunburn-free (clean) apples than pearl and control. Red color development for fruit was lower when nets were used. Interestingly, bitter pit incidence was lower underneath red nets for both years. Other than red color development, "Honeycrisp" fruit quality was not appreciably affected by the use of netting. These results highlight the beneficial effect of nets in improving light quality in orchards and mitigating physiological disorders such as bitter pit in "Honeycrisp" apple.
ABSTRACT
The costs of two reduced-fungicide programs (5 applications each) and two micronized wettable-sulfur programs (6 or 11 applications each) and their impact on scab control and fruit quality were evaluated on 'Contender' and 'Cresthaven' peach over two growing seasons. The reduced-fungicide programs consisted of applications of chlorothalonil and captan or chlorothalonil, azoxystrobin, and captan. All programs provided excellent scab control when disease pressure was low to moderate; however, six sulfur applications did not adequately control scab under high disease pressure. The product cost of the reduced-fungicide chemicals was higher, but comparable with six applications of micronized wettable sulfur or nine hypothetical applications of nonmicronized wettable sulfur per season. The reduced-fungicide programs were preferable to weekly applications of sulfur (11 applications) because they equally controlled scab at a reduced cost and have greater potential to protect against other summer diseases. The fungicide program effects on fruit quality were inconsistent. A more detailed study is needed to determine if a relationship between fungicide programs and fruit quality exists.
