Phytophthora boehmeriaeRevealed as the Dominant Pathogen Responsible for Severe Foliar Blight ofCapsicum annuumin South India

Abstract

Prior to 2011, foliar blight was not reported as a serious threat to hot pepper cultivation in India. During the June-to-January cropping season of 2011 and 2012, severe foliar blight epidemics were observed in Karnataka and Tamil Nadu states of India. In all, 52 Phytophthora isolates, recovered from blight-affected leaf tissues of hot pepper from different localities in Karnataka and Tamil Nadu states between 2011 and 2012, were identified: 43 isolates as P. boehmeriae and 9 isolates as P. capsici, based on morphology, a similarity search of internal transcribed spacer sequences at GenBank, polymerase chain reaction (PCR) restriction fragment length polymorphism patterns, and species-specific PCR using PC1/PC2 and PB1/PB2 primer pairs. The isolates were further assessed for metalaxyl sensitivity and aggressiveness on hot pepper. All isolates of P. boehmeriae were metalaxyl sensitive while P. capsici isolates were intermediate in sensitivity. P. boehmeriae isolates were highly aggressive and produced significantly (P < 0.01) larger lesion than those of P. capsici isolates. Thus, emergence of P. boehmeriae was responsible for severe leaf blight epidemics on hot pepper in South India, although it is not serious pathogen on any crop in any part of the world. These results have epidemiological and management implications for the production of hot pepper in India.

A unique species in Phytophthora clade 10, Phytophthora intercalaris sp. nov., recovered from stream and irrigation water in the eastern USA

“…P. kernoviae is an invasive pathogen to many forest and ornamental plants in the UK and presents a significant threat to global biosecurity (Brasier et al, 2005). P. boehmeriae causes a variety of diseases on a number of host plants such as brown rot of citrus fruits (Erwin & Ribeiro, 1996), foliar blight of hot pepper (Capsicum annuum) (Chowdappa et al, 2014) and boll rot of cotton (Gossypium sp.) (Erwin & Ribeiro, 1996).…”

A rapid in vitro leaf inoculation assay to investigate Phytophthora palmivora–coconut interactions

“…Segments of 1 × 1 cm size were surface sterilized by rinsing with a 0.01% mercuric chloride solution followed by washing in sterile distilled water thrice. Direct plating method (Chowdappa et al., 2014) was used to isolate pathogen by placing the leaf segments in carrot agar medium supplemented with rifampicin (125 ppm). The inoculated samples were kept in a growth chamber with a constant temperature (25 ± 2ºC) and humidity (95%).…”

Metalaxyl-resistant mutant strains of Phytophthora boehmeriae are as aggressive and fit as their metalaxyl-sensitive wild-type parents

“…Phytophthora blight caused by Phytophthora boehmeriae Saw. is a limiting factor for the production of cotton, ramie, citrus, black wattle, chili, and several other plants (D'Souza et al 1997;Ho and Lu 1997;Elena and Paplomatas 1998;Thomidis et al 2002;Dos Santos et al 2006;Wu et al 2010;Chowdappa et al 2014;Alves et al 2019;Thorpe et al 2021). In China, P. boehmeriae is the causal organism of cotton blight and ramie blight, causing destructive disease losses frequently (Ho and Lu, 1997;Chen et al 2001;Gao 2007;Wu et al 2010;Wang et al 2020a).…”