Avoiding Tomato and Potato Blight

The days have started getting slightly longer, the spring flowers have started pushing through albeit many of the early ones will be damaged by late frosts and the mail order seed packets have begun to arrive. Now is the perfect time to put in place your best hygienic planting practices to avoid the dreaded potato and tomato blights.

Before I discuss plant hygiene best practice I’d just like to give a brief rundown of the causes, effects and symptoms of the blight which so often spoils a great crop of tomatoes and potatoes. The blight is actually not a true fungus but rather an oomycete, commonly referred to as “water-moulds” the particular pathogen which causes the blight is phytophthora infestans. Stems and leaves of infected plants exhibit dark brown or black blotches which expand into black lesions resulting in leaf and stem death. The blight spores thrive and multiply in a warm damp atmosphere.

Prevention is better than cure

Follow the hygiene procedures listed below to minimise your chances of blight in your garden or allotment:

  • Thoroughly disinfect all of your gardening equipment which has been left in winter storage. It is suspected that the blight spores can remain dormant in soil for a number of years waiting for the right conditions to multiply and spread. Using a propriety garden disinfectant can help reduce the risk of blight to your crops.
  • Minimise moisture catch points on exposed leaves and stems. This can be achieved by a thorough caning and tying of tomato plants to prevent them from drooping over. Also trim any over lapping leaves and don’t plant specimens too close together.
  • Tomato plants grown under glass are generally less prone to infection; this is due to the main cause of blight being wind born spores from other infected gardens or plots.
  • At the first sign of any suspected infected growth remove it immediately and dispose of by burning. Keep a close eye out for any further signs of blight.
  • When choosing which tomatoes and potatoes to plant try to select a blight resistant cultivar – although by no means guaranteed, these blight resistant cultivars will significantly reduce your risk of contracting blight.
  • Keep an eye on the weather – as mentioned above phytophthora infestans thrives in warm moist weather and usually does its worst in warm wet summers.
  • There is a useful website https://blight.ahdb.org.uk/BlightReport where you can track reports of blight outbreaks in your area.

If you do lose a crop of potatoes or tomatoes to blight don’t let it get your spirits down – it has happened to all of us gardeners – just dig out the infected plants and burn them – a four year crop rotation is always good practice on your vegetable plot or in your allotment and really does help reduce the risk of blight.

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