Potatoes are subject to many plant diseases. One of the more common blights that affect the potato plants is potato leaf roll virus. Sap sucking insects are the catalyst that initiate and spread this disease, aphids in particular.
Aphids transmit the disease via a 'luterovirus' to multiple plant species, in beets it causes Beet Western Yellows Virus. Aphids transmit the virus to multyiple Plants, Potato plants, serve as natural hosts. In potatoes the same luterovirus manifests itself as potato leaf-roll virus. The virus in addition to being spread by aphids can also be transmitted via previously infected tubers - don't save seed potatoes from a field that has been known to have had this virus in the past several years.
Insect control is the first step - a preventative measure taken against potato leaf-roll virus. As aphids feed on the plant, the virus is introduced into the vascular tissue and rapidly spreads and reproduces. Common sense dictates that if you have no aphids, and use disease free seed - you won't have to worry about potato leaf roll virus.
Herbal Deterrents, plants that deter aphids, include Nasturtiums, Basil, Wormwood, Spearmint, Southernwood, Pyrethrum/Chrysanthemums, Onions, Stinging Nettle and Garlic. Keeping these growing in proximity of Potato fields will reduce the odds of acquiring this disease. Attracting Lady Bugs and green lacewings to your garden are another trick in the anti-aphid arsenal.
Neem Oil is an eco-friendly botanical insecticide with low toxicity ratings that is useful for aphid control.
Chemical insecticides registered for use against Aphids should be applied early to mid season. Applying late in the season is pretty much useless.
Symptoms of Potato Leafroll Virus
1. The Leaves of potato plants infected with Potato Leaf roll Virus will curl and roll up - that's why they call it "leaf-roll". They will also display a chlorosis.Chlorosis is when diseased leaves do not produce enough chlorophyll. Chlorotic leaves are pale green to yellow, in extreme cases they are a yellow-white.
2. Potato Leaf-roll Virus hampers the plants ability to manufacture carbohydrates which produce the chlorophyll necessary for photosynthesis. Without adequate photosynthesis they will at the very least perform very poorly, or they will simply die.
3. The foliage frequently has a leathery feeling as well as brown and brownish - yellow spots along the ribs and veins which indicate dead or dieing plant tissue.
4. Growth will be stunted due to insufficient carbohydrates and chlorophyll.
5. The Potato tubers will display necrosis. Necrosis is a localized dying back of living tissue - basically dead spots which eventually give way to decay and rot spots. The necrosis generally increases during storage of the tubers.
No Potato Plants are 100% resistant to Potato Leaf-roll Virus. Some varieties however are more resistant than others and a handful do not display the 'necrosis' of the tuber - so even if the plant becomes infected, the potato itself - although of lower quality will still be palatable.
Russet Potatoes, particularly Russet Burbank are highly susceptible and should not be planted in or near a field that has been effected by Potato Leaf-roll Virus in past several years.
Potato Leaf Roll will also effect related crops such as Tomatoes.