Introduction

1. Introduction • Potato cultivation can be a profitable enterprise when a few basic precautions are taken. • Selection of healthy and disease free planting material is an important step to avoid diseases in potato nursery. Certified seeds must be used as planting material. • Diseases such as bacterial wilt, fungal wilt, powdery mildew, early blight, etc are common diseases found in potato nursery.

2. Bacterial Wilt Symptoms: Initial wilting of leaves accompanied by mild yellowing may affect only one side of the leaf. Later severe wilting, browning, desiccation of leaves and death of seedling occur. Vascular strands darken and grayish white slime exudes in cross section. Wilt disease develops rapidly at high temperatures. Control: Crop rotation with cereals and legumes, use of disease free seeds, crop sanitation, tuber dipping with 0.5% Aretan or Agallol suspension for ten minutes and soil treatment with Brassicol @ 20-30 kg/ha manage the disease at low level. A combination of seed and soil treatment gives the best control of diseases in potato.

3. Powdery Mildew of Potato Symptoms: Initially, infected leaves or stem exhibits whitish spore masses resembling like soil residues, dust or spray deposits. Management: In severe infection, spraying of sulfur formulations at 15 days interval through three sprays of fungicides like 0.2% Wettable Sulfur, 0.1% Tridemorph or 0.1% Dinocap is recommended. Infection of Powdery Mildew on Potato Leaf Infection of Powdery Mildew on Potato Leaf

4. Verticillium Wilt of Potato: Symptoms: Disease occurs in tropical, subtropical climatic regions. Yellowing of basal leaves follows wilting of plant. Vascular system of lower stem turns brown. Disease causing fungi survives in soil, plant debris and on host plants. Management: Follow Crop rotations with legumes, use disease resistant varieties, timely irrigation and foliar application of Benlate (0.1%) is effective. Unilateral Leaf Necrosis And Wilt in Potato Vascular Discoloration of Potato Stem (Top) Non-affected Stem (Bottom).

5. Potato Leaf Roll Virus (PLRV) Symptoms: Disease is transmitted by aphids. Upper leaves roll towards base, rolls are stiff, leathery and under side becomes tinged purple. Plants are stunted and erect. Upper leaves are pale. Crop yield losses may reach up to 90%. Infected Potato Plant by PLRV Management: Select healthy plants from nursery, eliminate diseased plants through rouging. Spraying systemic insecticides decrease vector (aphid) infestation and disease spread. PLRV can be effectively eliminated from tubers by heat treatment.

6. Potato Viruses Y and A (PVY and PVA) Symptoms: These viruses are transmitted through aphids. bunching, twisting of leaves, downward turning of leaflet margins, stunting, necrosis of veins, necrotic spotting, leaf necrosis and stem streaks are typical symptoms. The yield reduces up to 80%. Management: PVY and PVA diseases are controlled by elimination of aphid infestation, clonal selection of seedlings, rouging of diseased seedlings, use of resistant cultivars. PVA Infected Leaf of Potato PVY Infected Leaf of Potato

7. Cyst Nematodes Symptoms: Stunting, yellowing and early maturing of leaves. White/yellow spherical female nematode (0.5-1.0 mm diameter) seen on potato roots. They turn into brown cysts containing eggs persisting for several years. Cysts are carried by soil sticking to tubers, farm machinery, tools and containers. Management: Useof nematode Resistant varieties, long crop rotation, high doses of organic matter. Use of Nematicides and soil fumigants. Cyst Nematodes on Potato Roots Symptoms on Potato Leaves