Phytopthora blight of pigeon pea

Phytopthora blight of pigeon pea

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  Phytophthora Blight OfPigeonpea • Phytophthora blight (PB), caused by Phytophthora drechsleri f. sp. Cajani. • The first suspected occurrence of PB on pigeonpea in India was reported in 1966 by Williams et al. • It is the third potentially important disease of pigeonpea after Fusarium wilt and pigeonpea sterility mosaic disease. • Geographic Distribution:- The disease has been reported from India, Kenya, Panama and Australia etc.
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  Symptoms • Infection seedlingsis visible as water soaked lesions in the trifoliate leaves which subsequently become necrotic . • The leaflet lesions are circular to irregular and up to 1cm in diameter . The whole foliage can exhibited a blighted appearance under conditions of high humidity. • On stem brown to dark brown lesions distinctly marked from the healthy green portion are formed near ground level.
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  Leaf and Stemsymptoms Leaf symptoms Stem symptoms
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  Contd.. • The lesionson the stems and branches increases rapidly, causing the portion of the plant above the lesions to dry out but remain attached to the plant . Wind easily breaks up stems at the infected point. (Fig 3) • Some infected pigeonpea plants often produces large galls on their stems.(Fig4)
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  Fig 3 andFig 4
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  As the diseaseprogress , patches of diseased plant become conspicuous in the field from a distance
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  Pathogen • Caused byPhytophthora drechsleri f. sp. Cajani. Classification of Pathogen:- Kingdom – Fungi Phylum- Heterokontophyta Class - Oomycota Order- Peronosporales Family- Peronosporaceae Genus- Phytopthora Species- cajani
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  Etiology • Sporangium variedin different isolates from broadly oval, pyriform to elongate and nonpapillate • Sporangia of P. drechsleri f.sp cajani are of proliferating type with avg size (61.8 x 37.3mm)
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  Disease cycle • Thedisease is soil borne. The fungus survives as dormant mycelium in soil and in infected plant debris • Wind and rain help to disseminate zoospores and by damaging the plant. • Pigeonpea gradually develops tolerance to the disease as they grow older and not infected after ther are 60 days.
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  Favourable conditions • Cloudyweather and drizzling rain and temperature of 25 degree celsius and leaf wetness of 8 hrs favorable for disease development • Warm and humid weather following infection results in rapid disease development
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  Management • Resistant varietiesHY 4, ICPL 150, ICPL288, ICPL304, KPBR80-1-4, KPBR80-2-1 Suggested cultural practices :- • Select field with no previous record of blight. • Avoid sowing pigeon pea in the fields with low lying patches that are prone to water logging • Prepare raised seeded and provide good drainage • Use wide inter row spacing.
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  Management • Seed dressingwith Ridomil M Z @3g kg-1 seed • Two foliar sprays of Ridomil M Z @ at 15- day interval starting from 15 days after germination