Pepper Wilt Research Articles

Plant Phenology Influences the Effect of Mycorrhizal Fungi on the Development of Verticillium-induced Wilt in Pepper

Verticillium dahliae alters water status and consequently, growth and production of pepper plants. On the other hand, arbuscular mycorrhizal fungi (AMF) can reduce damage caused by specific soil-borne plant pathogens and improve drought resistance of pepper. Therefore, one objective of this research was to assess if AMF can modify the development of Verticillium-wilt in pepper plants. A second objective was to study the influence of plant phenology at the moment when V. dahliae was inoculated on the possible biocontrol of the disease by AMF. Results suggested that AMF reduce the deleterious effect of V. dahliae on pepper growth and yield. However, bioprotection against Verticillium-wilt was conditioned by plant phenology at the moment of pathogen attack. The highest efficacy of AMF occurred when V. dahliae was inoculated during the vegetative stage of plants. AMF allowed leaf relative water content to be maintained for longer and delayed both the appearance of disease symptoms and the decrease of photosynthesis in Verticillium-inoculated plants. These benefits on plant physiology increased pepper yield.

Alleviation of verticillium wilt in pepper ( Capsicum annuum L.) by using the organic amendment COA H of natural origin

Pepper seedlings cv. “Piquillo” were grown for 3 months in unamended medium with organic growing medium COA H (containing salicylic acid (SA), soluble ammonium salts and sea weed extract from Ascophyllum nodosum) inoculated or not inoculated with Verticillium dahliae Kleb. and in amended growing medium with COA H inoculated or not inoculated with V. dahliae. Seedling growth parameters, leaf content of relative water and chlorophyll, leaf gas exchange and resistance as well as total phenolics in stems were determined on days 0, 7, 21, 28 and 33 after inoculation with V. dahliae. SA in stems was measured on days 0, 21 and 33 and leaf nutrient content was analysed on day 33. Results indicate that the organic amendment COA H delayed senescence in Verticillium-inoculated seedlings. In fact, inoculated seedlings that received COA H always exhibited similar leaf resistance to water vapour as well as leaf content of chlorophyll, relative water and nutrients to their relative healthy controls. By contrast, the content of chlorophyll a and relative water in leaves from unamended seedlings significantly decreased on days 21 and 28, respectively, reaching values 30 and 20% lower than those found in the unamended healthy controls. Likewise, the content of chlorophyll b, potassium (K) and magnesium (Mg) in leaves from unamended seedlings inoculated with V. dahliae had declined 35, 40 and 50%, respectively, of the control values by day 33 after pathogen inoculation. On the other hand, while Verticillium-inoculated seedlings grown in amended medium with COA H maintained control photosynthetic rates for 21 days after inoculation, CO 2 exchange rates decreased from day 21 in unamended ones and the leaf resistance in these seedlings enhanced 50% 1 week after inoculation. In addition, Verticillium-inoculated seedlings supplied with COA H delayed the appearance of disease symptoms and their disease index on day 33 was about 40% lower than that measured in unamended pepper. The early accumulation of phenolics (from day 7 after inoculation) in pepper grown in amended medium with COA H could be involved in the greater disease resistance and/or tolerance exhibited by these seedlings.

Epidemiology of Tomato Spotted Wilt in Pepper and Tomato in Southern Georgia.

The spatial distributions of symptomatic tomato and pepper plants infected with tomato spotted wilt virus (TSWV) were mapped over time in field studies in 1990 to 1992. Disease gradients occurred in some tomato transplant beds and pepper fields but were not observed in tomatoes grown to maturity. In 1990 and 1991, an increasing gradient emanated from the eastern edge of tomato transplant beds and led to adjacent tobacco plots containing TSWV-infected plants. In addition, gradients within each block emanating from the edge adjacent to fallow alleys were observed within the primary disease gradient in 1990. A gradient also occurred both down the row and across cultivars in a commercial pepper field in 1990. The gradient failed to flatten over time, a possible indication of lack of secondary disease spread. Tests for aggregation supported the contention that there was limited secondary spread within pepper fields and tomato plots and that most infections arose from primary transmission. Clipped plants from tomato transplant beds had no higher incidence of TSWV in grow-out tests than did nonclipped plants. Reduced yields were significantly correlated with time of first symptom expression in tomato, with plants that were symptomatic earlier in the season yielding less fruit per plant by weight.

Nucleotide sequence of a strain of tobacco etch virus that does not cause Tabasco pepper wilt.

Nucleotide sequence of a strain of tobacco etch virus that does not cause Tabasco pepper wilt.

Managing Thrips and Tomato Spotted Wilt in Pepper

Thrips are serious pests of ornamental, vegetable, and fruit crops in the field and greenhouse. Feeding and egg-laying by thrips results in distortion, discoloration, silvering, and bronzing of leaves and fruits of vegetables reducing their market value. Some species of thrips are vectors of bunyaviruses (family Bunyaviridae, genus Tospovirus, type species Tomato spotted wilt). Severe epidemics occur annually on food, fiber, and ornamental crops in temperate, subtropical and tropical regions of the world. This document is ENY-658, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date printed: March 2004.
 ENY-658/IN401: Managing Thrips in Pepper and Eggplant (ufl.edu)

Pepper wilt disease

Pepper wilt disease