Kaolin reflectant treatments have been shown to reduce stress due to the environment, pests, and pathogens in many plants. We tested the effect of kaolin on yield, beet curly top virus (BCTV) incidence, and physiological parameters (measured as hyperspectral reflectance) of field-grown chile pepper (Capsicum annuum L.) in southern New Mexico. Curly top incidence was significantly lower in kaolin-treated chile blocks than untreated blocks. Peppers treated with the kaolin-reflectant showed significantly less water stress and higher photochemical reflectance than untreated plants during active growth periods. Treated plants had significantly higher levels of chlorophyll a and higher reflectance than untreated plants. Yield from treated plants was not significantly different from that from untreated plants. We did not detect any deleterious effects on peppers due to application of kaolin. Kaolin treatments suppressed beet curly top virus on chile and reduced water stress parameters during the hottest months of the growing season, suggesting that it would be useful in New Mexico chile production in years with moderate disease pressure.

No abstract

No abstract

Verticillium wilt, caused by Verticillium dahliae, is an economically important disease on chile pepper (Capsicum annuum L.), which is grown primarily under furrow and drip irrigation in New Mexico. Field observations by producers indicate that Verticillium wilt is more prevalent on chile pepper grown under drip irrigation than under furrow irrigation. To test these observations, chile pepper plants at the six- to eight-leaf stage inoculated or noninoculated with V. dahliae were subjected to either periodic flooding or no-flooding conditions in the greenhouse. Plants under periodic flooding were subjected to three events of 7 day flooding and two events of no flooding over a period of 5 weeks. Differences among treatments were assessed using disease severity, plant dry weight, and spectral reflectance-based physiological indices such as moisture stress index (MSI), chlorophyll-based difference index, water band index, and photochemical reflectance index (PRI). There was a significant interaction between flooding and inoculation with respect to disease severity (P < 0.003). In plants inoculated with V. dahliae and subjected to periodic flooding, the relative treatment effect (RTE) based on disease severity was increased from 40% to 130% relative to noninoculated plants subjected to no flooding. However, under conditions of no flooding, RTE increased by ≈200% to 286% when plants were inoculated with V. dahliae relative to noninoculated plants. In general, periodic flooding and inoculation with V. dahliae were accompanied by a decrease in plant dry weight as well as in the level of spectral reflectance-based physiological indices. In noninoculated plants subjected to periodic flooding, plant dry weight was reduced by ≈45% to 50% relative to noninoculated plants subjected to no flooding. In plants inoculated with V. dahliae and subjected to periodic flooding, reduction in plant dry weight was ≈46% to 60% relative to noninoculated plants subjected to no flooding. Under conditions of no flooding, plant dry weight was reduced by ≈33% to 52% when plants were inoculated with V. dahliae relative to noninoculated plants. Of all the spectral reflectance-based physiological indices, PRI was the most affected by flooding and inoculation. For noninoculated plants, the mean area under the curve for PRI (AUC-PRI) was decreased by ≈90% under periodic flooding relative to no flooding. In plants inoculated with V. dahliae and subjected to periodic flooding, reduction in AUC-PRI was ≈93% relative to noninoculated plants subjected to no flooding. Under conditions of no flooding, AUC-PRI was reduced by ≈93% when plants were inoculated with V. dahliae relative to noninoculated plants. These results showed that chile pepper growth and physiology were affected similarly by flooding and inoculation with V. dahliae. However, severity of Verticillium wilt was greater under no-flooding than under periodic flooding conditions.

No abstract