Growing potatoes

Potato Viruses Y and A (PVY and PVA) is the second most important potato virus. It is perpetuated through infected tubers and transmitted by aphids in a nonpersistent manner. Potatoes yield losses may reach 80%.

Symptoms of Potato Viruses Y and A

Symptoms of Potato Viruses Y and A vary widely with virus strain,Potatoes  cultivar, and environmental conditions.
Rugosity, bunching, twisting of leaves, downward turning of leaflet margins, stunting, necrosis of leaflet veins, necrotic spotting, leaf necrosis, and stem streak are typical.
Less sensitive potatoes cultivars may react by developing with only a mild mosaic, or they may be infected symptomlessly.
PVA is in many respects similar to PVY.
When present in certain cultivars, it is generally less severe than PVY.
Potatoes yield losses may reach 40%.
PVA causes mosaic (sometimes severe), as well as rugosity and crinkling, and leaves may appear shiny.
PVA symptoms are usually milder, but cannot be easily distinguished from those of PVY.

Management

Management of PVY and PVA is by clonal selection and roguing in seed propagation. Resistant potatoes cultivars are available.

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September 11th, 2009 | Tags: POTATO, VIRUS A, Viruses Y | Category: Diseases Caused by Viruses, Potato Diseases | Leave a comment

Potato Leafroll Virus (PLRV)  is the most important potato virus and occurs common in all groung potatoes countries. Potatoes yield losses in highly susceptible cultivars can reach 90%.

Symptoms of disease caused by Potato Leafroll Virus

Primary symptoms caused by currentseason aphid-transmitted infection are rolling of upper potato plants leaves, especially of leaflet bases. These leaves tend to be upright and are generally pale yellow.
With many cultivars, they are tinged purple, pink, or red. Late infections may not cause symptoms, whereas some cultivars are infected symptomlessly.

Potato tubers of highly sensitive cultivars develop net necrosis in the flesh. Secondary symptoms (of plants grown from infected tubers of subspecies tuberosum) are rolling of basal leaves, stunting, upright growth, and paleness of upper leaves.

Rolled leaves are stiff and leathery, and sometimes tinged purple on their undersides.

Subspecies andigena reacts differently: it develops marginal and interveinal chlorosis, especially of upper leaves, marked upright growth, and often severe stunting.

Rolling of lower leaves is usually lacking. Natural transmission is by aphids in a persistent manner, and through infected tubers.

Management

Potato Leafroll Virus can be managing by selecting healthy plants gor growing and eliminating diseased plants through roguing in seed propagation.

Systemic insecticides will decrease spread by aphids within the crop but will not prevent infection by viruliferous aphids from other fields.
Potato Leafroll Virus is the only potato virus known to be eliminated from tubers by heat treatment.

Resistant potatoes cultivars have been developed recently.

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September 11th, 2009 | Tags: management, Potato Leafroll Virus, symptoms | Category: Diseases Caused by Viruses, Potato Diseases | Leave a comment

Fusarium wilt potato disease is ossurd by different Fusarium spp.
Verticillium wilt is caused by the fungi Verticillium alboatrum and V. dahliae.
These fungi attack a wide range of plant species, including cultivated potatoes crops and weeds. They are soil borne in field and greenhouse soils where they can persist for many years.
Although disease is retarded by the higher temperatures that favor Fusarium wilt, visible symptoms may appear to be more severe when high temperatures exist, due to restricted water movement in the plant brought about by damage done to the water conducting vessels earlier in the growing season.

Fusarium and Verticillium fungi are widespread potatoes diseases and persist several years in soil.
To reduce populations of these fungi is necessary a long crop rotation (4 to 6 years).

Avoid using any solanaceous crop (potato, tomato, pepper, eggplant) in the rotation. In case of Verticillium wilt also avoids the use of strawberries and raspberries, which are highly susceptible.
Rotate with cereals and grasses wherever possible.
It is important to keep rotational crops weed-free. As there are many weeds hosts of Verticillium.

Whenever practical, remove and destroy infested potato plant material after harvest.
Maintain a high level of plant vigour with appropriate fertilization and irrigation, but do not over-irrigate, especially early in the season.
If soils are severely infested, production of potatoes crops may not be possible unless soil fumigation is an option.

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September 10th, 2009 | Tags: Control of Fusarium, Growing potatoes, solanaceous, Verticillium Wilts | Category: Diseases Caused by Bacteria, Potato Diseases | Leave a comment