Epidemiology of Phytophthora capsici on bell pepper

Abstract

SUMMARYThe number of pepper seedlings (Capsicum annuum L.) surviving transplanting in a glasshouse decreased from 100% in the control to 84 ± 6,55 ± 8, and 18 ± 6% in field soil containing 1, 5 and 25 propagules of Phytophthora capsici Leonian per gram soil, respectively. When detached leaves were inoculated with a sporangial suspension at 15 and 31 °C, an incubation period of 24 h was required before an infection level of 50% was reached. Incubation at 27 °C for 4 h resulted in 60% of the leaves infected. Neither sporangia nor mycelia survived a week in leaf tissue if the relative humidity was 47% or less or if the temperature was -12 or 40 °C. Recovery of sporangia from inoculated stem pieces (2 cm long) stored for 1 week at 25 °C was reduced from 1455 to 30 sporangia per stem piece when the relative humidity was reduced from 100 to 87%. P. capsici could not be isolated from inoculated leaf tissue 2 days after being placed on the soil surface in a field, but was easily isolated after 14 days if buried. The distribution of disease within a test field followed the field's drainage pattern. Splashing rain and run-off water appear to be the main means of spread. Combined rainfall for days 3, 4, 5 and 6 prior to symptom development correlated with disease incidence (r = 0·53, P < 0·01).

Rainfall and crop residue effects on soil dispersion and Beauveria bassiana spread to corn

“…Rainfall is important in dispersal of fungal and plant pathogens (Faulwetter, 1917a,b). In the absence of insects that can act as vectors of fungal spores, rain splash is critical to fungal spore transport (Gregory et al, 1959;Hunter and Kunimoto, 1974;Schub, 1983). However, the influence of these environmental factors on the spread of entomogenous fungi, for the most part, is unknown.…”

Dispersal of Phytophthora capsici and P. parasitica in furrow‐irrigated rows of bell pepper, tomato and squash

“…Similarly, P. capsici, with caducous sporangia (Stamps. 1985), can be splash-dispersed to be an aerial pathogen of peppers (Schlub. 1983;Bowers & Mitchell, 1991), tomato (Hartman ct ai, 1991) and other crops (Ramachandran et ai.…”

Implications of Irrigation Method and Amount of Water Application on Phytophthora and Pythium Infection and Severity of Root Rot in Highbush Blueberry

“…For example, localized systems such as drip, which apply water to only a small fraction of the soil, often increase root rot when disease pressure is high and irrigation is overapplied (Feld et al, 1990). Sprinkler systems, on the other hand, potentially increase dispersal of soil pathogens by splashing (Ristaino and Johnson, 1999) as well as increase the spread of fruit and foliar diseases (Schlub, 1983), but also tend to reduce sporangia formation and lower potential for zoospore release by distributing water more evenly (Berhardt and Grogan, 1982;Duniway, 1983). Utkhede and Smith (1996) found in apple (Malus domestica Borkh.)…”