Java downy mildew - Peronosclerospora maydis
EEffective: August 18, 2010 - May 14, 2020
Taxonomic Position:
Sclerosporales : Sclerosporaceae
Pest Type:
Fungi
Pest Code (NAPIS):
FFABPMD
This pest is a member of the following lists:
These Approved Methods are appropriate for:
2019, 2018, 2017, 2016, 2015
Pest is vectored by:
No known vector.
Survey
Approved Method(s):
Method |
Instructions |
NAPIS Survey Method |
Visual |
Collect symptomatic plants. Unsprayed, susceptible plants (sentinel plots) that are scouted regularly can be used for early detection. |
3031 - General Visual Observation
|
Signs:
Downy (grayish) fungal structures are observed on the chlorotic streaks.
Symptoms:
White to yellow stripes/streaks, which become necrotic and brown, are usually the first symptom observed.
When systemic, the pathogen causes severe chlorosis in the upper leaves.
Infected plants may be stunted and sterile and often lodge (fall over).
Plants may develop multiple and deformed cobs, leaflike tassels and cobs, combined tassels and cobs, and either elongated or shortened stalks.
Key Diagnostics
ID/Diagnostic: Morphological
Morphological: condiophore structure and dimension and spore (conidia) shape and size (Smith and Renfro, 1999).
Isozymes: comparisons have been used to identify Peronosclerospora spp., including P. maydis (Micales et al., 1988).
Mistaken Identities:
Peronosclerospora spp. and other downy mildew genera (including Sclerospora and Scleropthora).
In Progress / Literature-based Diagnostics:
Molecular: Some DNA-based approaches have been reported for other Peronosclerospora spp., which indicates that a molecular method for identification may be available in the future.
Yao et al. (1991a) created a DNA clone that could be used as a species-specific hybridization probe for the detection and identification of P. sorghi.
Yao et al. (1991b) then developed a DNA probe from a P. maydis genomic library to detect P. sacchari in corn leaves and seeds.
Ladhalakshmi et al. (2009) used a DNA sequence characterized amplified region (SCAR) marker for identification of isolates of P. sorghi from corn using PCR.
There has been some work on SSR markers for P. sorghi and related species that include this pathogen and will be helpful for identification and future PCR primer development (Perumal et al., 2008).