Fight the Blight.................
I read on someone else's blog the other day that "you should never water onions & potatoes" which seems strange, but I can't find the entry now. Potatoes need lots of water to yield a good crop, and the time to start is when the very first flowers appear. Dr Hessayon says "Water liberally in dry weather - This is most important once tubers have started to form." Commercial growers usually work to the rate of 2 gallons per square yard, and will apply this regularly in hot conditions.
One of the reasons why some folk are cautious about watering their 'taters, is that the prime watering time of mid June to mid August, is also the dreaded potato blight season, and this most devastating disease thrives in hot humid conditions.
The best way to avoid blight is by knowing how it is spread. The following is good practice, and was explained by Stefan Buczacki on his Garden Questions program on one of the cable channels today....( See - daytime TV can be good for you!)
1. Contrary to many people's belief, blight does not live in the soil. It is a fungal strain, who spores are borne on the wind over long distances.
2. The spores lands on the leaves, and will remain there in very dry weather. They cannot "travel" through the plant, but require rain (or watering) to wash them down the stems into the soil, where they attack the tubers. Therefore hot rainy summers will almost always result in various degrees of blight on intensively cultivated allotments. New potatoes will probably harvested by then, but main and late crops can be ruined if left unchecked. Although you can now get quite a few good blight resistant varieties.
3. Now you know how the spores reach the spuds, make sure that when you water, you keep the hose or watering can nozzle right down at the base of the stems, at ground level, and water each plant individually. This way you will avoid washing spores down the plant as much as possible. If using a hose, take the pressure jet off the end to eliminate too much spray.
4. If you do get an attack of blight, as soon as you see the leaves turning a sickly yellow and black, (this is very rapid as opposed to natural dying off) immediately cutting the helms right down to ground level may well save the crop underneath. Burn any infected material, or bag it up for disposal off the site.
5. Although it can't live in open soil, blight will remain in any stray tubers, so make sure when lifting the crop, that you remove every last little one....And don't throw them on the dump....take them off site and bin them. Re-infection from last year's compost heap is one of the most common sources of the disease.
But certainly don't let the fear of blight stop you from watering your spuds....(Sounds like a euphemism for something rude... Ed.)