Basal stem rots
Phoma spp.
What is Basal Stem Rot ( Phoma medicaginis)?
Pea (Pisum sativum) Ascochyta Blight, also known as Basal Stem Rot or Black Stem, is a disease complex caused by Phoma medicaginis var. pinodella, Ascochyta pisi, and Mycosphaerella pinodes. It affects pea plants and can cause stem, crown, foliar, and pod diseases. Ascochyta blight affects seedlings in cool, wet weather, causing blackening and death of stem tissue from the soil line and extending up the stem for 2 to 6 inches. Later, it leads to severe spotting on leaves, stems, and pods. The disease is distributed in pea-growing regions worldwide.
How does Basal Stem Rot ( Phoma medicaginis) occur?
Pea Ascochyta Blight is primarily reproduced through infected seeds. The pathogens Phoma medicaginis var. pinodella, Ascochyta pisi, and Mycosphaerella pinodes can all be transmitted through contaminated seed material. The pathogens can survive in the soil as thick-walled chlamydospores for extended periods. Infected plant debris, such as pea straw, can also contribute to the disease's persistence.
Symptoms
1 - Impacts on Plants
Pea Ascochyta Blight significantly reduces pea crop yield and quality, leading to lower productivity and diminished overall quality of the harvested peas.
Solutions
1 - Cultural practices
1. Crop rotation: Rotate out of peas for at least 4 years and avoid including vetch or alfalfa in the rotation. 2. Seed selection: Use seed from pathogen-free fields and avoid saving seed from affected fields. 3. Straw management: Burn or plow under diseased pea straw after harvest to reduce inoculum sources. 4. Planting timing: Plant midseason to late-maturing varieties or delay planting by 2 weeks to reduce disease incidence.
2 - Applications of Funigicides
Some available fungicides for treating Ascochyta blight in peas include Captan, Mertect, Nevado, Thiram, Rovral, Wakil XL, Aprovia Top, Cueva, Endura, Priaxor Xemium Brand, Proline 480 SC, and Strobilurin fungicides. Consult local regulations and experts for specific recommendations.
