FACT- FILE [Potato Pests 01]
Potato Blight Fact-Sheet
How to Identify Potato Blight
The first signs of potato blight are dark brown markings on the edges of the potato plant leaves.
The next stage is that the leaves curl and the whole potato plant wilts and eventually falls over. This happens extremely quickly and the whole process can take only a matter of days.
Burn the foliage immediately because this is a highly infectious disease. The spores will live in the soil for a couple of years if they are not destroyed. The same fungus also causes Tomato Blight.
If the foliage is destroyed immediately Potato Blight is noticed, there is a very good chance that the potato tubers under ground will be unaffected. Growth of the potato tubers underground will be slow when the foliage has been destroyed but they will be edible and will store for some time in the ground. See the picture below to identify if the potato tubers have been affected.
Treatment of Potato Blight
1. Destroy all infected plants by burning them. Do not plant potatoes (or tomatoes) on the same patch of land without leaving an interval of three years.
2. Spray potato and tomato plants with Bordeaux Mixture (available at most garden centres) in May and June to help prevent infection.
Avoid it occurring in subsequent years by good crop rotation and burning all infected plants as soon as the disease is noticed.
on Potato Blight
Watch Out for Potato Blight
Gardeners and allotment owners are being urged to be on the look out for potato blight this summer, the disease that caused the Irish potato famines in the 1840s. Experts say that more and more outbreaks of blight are originating from allotments and gardens. These can spread to other gardens and allotments, but also affect commercially grown potatoes.
Gary Collins, Technical Executive with the Potato Council, said: “In the current climate more people are growing their own potatoes. As potato blight is a major concern to the industry, we keep a check on where outbreaks are coming from. Between 2007 and 2008 the number of outbreaks from allotments and gardens more than doubled. Because potato blight can spread very easily over large distances, everybody needs to keep a close eye on their potatoes. Not only can it reduce the quality of your home-grown crop, but also your neighbour’s crop, and the local farmer’s crop too. A little knowledge and effort can go a long way to reducing the impact of this disease”
Blight is most likely to appear between July and September, particularly when the weather is warm and humid. Gardeners should look out for dark brown or blackish patches or lesions on the top of the leaflets , often surrounded by a pale yellow halo. These lesions may also be found on the stems . Under humid conditions, there may be a downy white coating that looks like fine cotton wool developing on the underside of the leaflets, or again on the stems. Blight spores released from this white coating is how the disease spreads from the foliage to other plants, or down on to the soil, where they can infect the tubers, causing sunken areas on the potato surface, and a chestnut-coloured rot under the skin.
If you discover what looks like potato blight you should snip off the leaflets, or even whole stems to stop the disease spreading and remove them from the crop. If vigilant, this may slow the spread to a point where the crop is unharmed, and you will have done your bit to help reduce the spread of blight. The potatoes can still be harvested after two to three weeks. Make sure you remove all the potatoes from the ground, and do not leave any in the soil or on garden tips.
Tips for preventing blight include:
To find out more about potato blight, visit www.potato.org.uk/blight for an in-depth fact sheet. On this site, you can also register free to receive weather warnings that let you know when the conditions are right for the spread of blight - known as a Smith Period, or that there may be blight in your area. These are sent by email and as a text message.
Note to editors
· Potato Council is part of the Agriculture and Horticulture Development Board www.ahdb.org.uk working on behalf of British potato growers and purchasers to promote potatoes. Potato Council is funded through a statutory levy on 3,000 potato growers and potato trade purchasers and aims to support the British potato industry
· Please below a Fact Sheet with more information on blight.
Potato Blight – The Facts
The signs of potato blight are:
Those growing their own potatoes can take a number of steps to ensure that there is a reduction in the likelihood of blight occurring:
o Always buy your seed potatoes from a reliable source. Do not bring seed potatoes from another country, or save your own as they may be infected.
o Some maincrop varieties show some resistance and are slow to develop blight.
o Always remove all potential sources of blight. Harvest even the tiniest potatoes, and remove any potatoes that grow by themselves (volunteers).
o Never abandon old tubers around the garden or allotment, or try to compost them.
o Remove blighted tubers before storing, and always store your potatoes under dark, cool conditions.
o Avoid planting in sheltered sites and plant in rows into the wind if possible.
o If watering is required apply to the base of the plants, soil improvement and mulching will reduce the amount of watering required.
o Blight spores on foliage are washed down through the soil to infect tubers. Earthing up potatoes, or mulching the soil with hay or straw can reduce levels of infection.