Check your potatoes as it looks like blight has arrived. It may help if you cut off the the leaves to prevent the blight contaminating your potatoes.
See this post from the RHS
https://www.rhs.org.uk/advice/profile?pid=217
Non-chemical control
Infected material should be deeply buried (more than 45cm deep), consigned to the green waste collection or, ideally, burned rather than composted
Earthing up potatoes provides some protection to tubers Early-harvested potatoes are more likely to escape infection Gardeners are able to access forecast warnings of when blight is active, or when there have been confirmed cases, in their region (visit the Fight Against Blight website),
Picking off leaves or leaflets when just a few are affected may slow down the progress of the disease very slightly, but will not eradicate the problem When infection levels reach about 25 percent of leaves affected or marks appear on stems cut off the foliage (haulm), severing the stalks near soil level and raking up debris.
When the skin on tubers has hardened, after about two weeks, the tubers can be dug up. To prevent slug damage avoid leaving tubers in the soil after this time Use the tubers from blighted crops as soon as possible, checking any stored tubers regularly for decay
Operate a rotation to reduce the risk of infection, ideally of at least four years
Destroy all potatoes left in the soil, and any waste from storage, before the following spring
The genetic population of the fungus is ever changing and new findings have shown that one dominant new strain seems to have overcome major gene resistance. In the past some potato varieties had shown some resistance, these included ‘Cara’, ‘Kondor’, ‘Orla’, ‘Markies’ and ‘Valor’, but this is not currently effective.
The ‘Sarpo’ range exhibit more effective resistance than other cultivars. Some old favourites are very susceptible, eg ‘Arran Pilot’, ‘King Edward’, ‘Majestic’, ‘Sharpe’s Express’. Varieties that were previously rated resistant have been retested against this new dominant strain and the results have been published.
Tomatoes are generally very susceptible, but the varieties ‘Ferline’, ‘Legend’ and ‘Fantasio’ are claimed to show some resistance. Even these varieties, however, will eventually succumb in wet, warm weather. It is probably best not to rely on host resistance for blight control in tomatoes.
Chemical control
There are currently no fungicides available for use by gardeners against blight on potatoes or tomatoes.
Comments