Dealing with diseases

Picture from the collection

by Tony Hollander

Tackling potato blight

The warm spring and wet summer in 2007 created the ideal environment for potato blight to flourish....and it did. Even if the July floods had never happened, many plot-holders would have lost their entire potato crop because of this rapidly-spreading and destructive disease. The bad news is that, because we had potato blight in 2007, we are very likely to get it again in 2008. So what can we do about it?

All the experts are agreed on tackling potato blight. This is what you do:

  1. To prevent blight, spray Bordeaux Mix (or other copper fungicide), pbi Dithane or mancozeb over each entire potato plant in early July.
  2. Repeat this spraying once or twice at three-weekly intervals, but more often if heavy rain washes away the spray.
  3. If blight attacks your potato plants, extra earthing up may help prevent the disease from spreading to the actual tubers. You should certainly cut off and bin all infected foliage, but never put this on your compost heap. Remove it from the allotment site.
  4. Try growing blight-resistant varieties, such as Maris Peer, Pentland Crown, Sarpo Mira or Sarpo Axona.

NB. You can buy Bordeaux Mix from Trap Trading. Also note that potato blight may infect tomato plants.

Other diseases

  • Cover cabbage plants with fleece to prevent whitefly - also available from Trap Trading
  • Environmesh protects against carrot rootfly, as does not leaving them in the ground too long in autumn