< tilbage 29-11-2024 - 11:26

Identification and Field Handling of Aphanomyces euteiches on Pea (Pisum sativum).

Aphanomyces euteiches is a destructive soilborne plant pathogen. This oomycete organism survives in the soil for decades and infects and degrades roots of plants from 11 families. Infected roots develop a golden-brown color, begin to disintegrate and the entire root system is destroyed. Symptoms of Aphanomyces root rot are gray and water-soaked roots and as the disease progresses, the roots become golden-brown, decayed and soft. Aboveground symptoms such as chlorosis and necrosis of leaves at the base of the plant follows. In the advanced stages of root rot, the cortical tissue surrounding the vascular tissue begins to slough off and can be removed easily.

A. euteiches can be isolated from both infested soil and infected plant tissue.

The initial inoculum in the soil are oospores that produce zoosporangia and than zoospores. The movement of the zoospores toward the host requires free water in the soil. Therefore, symptoms often can be seen in low places within a field, in areas with poor drainage or high clay content. The optimal temperatur for infection is 23 to 24°C.

Ekoplan Aps use a soil baiting technique for isolating A. euteiches directly from soil. Approximately 10 soil samples per 5 ha are taken from a single field (approximately 5 liters total) in a zig-zag pattern from the top 15-20 cm and mixed. The soil is placed into pots. Seeds of a susceptible pea cultivar are placed on top of the soil and covered with approximately 5 cm of the mixed field soil. Pots are kept at approximately 24°C, and soil is watered daily under greenhouse conditions. Plants are harvested and evaluated for A. euteiches symptoms after 28 days and roots are examined for A. euteiches oospores.

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