|Why do my hosta leaves start to turn brown and dry up about mid July? Also why do some of my leaves have holes in them about a month after they are fully grown? I looked for bugs,but I don't see any. Help! Jackie Ebling D. M. Ia.|
|Hostas grow best in cool weather so it could be that hot, dry air is dessicating them. Or, they may be showing signs of fungal infection. Anthracnose is a fungal leaf disease of hosta that thrives in warm, wet weather.
Symptoms of hosta anthracnose include large, irregular spots with darker borders. Eventually the centers of the spots fall out, and leaves become ragged. Usually this disease doesn't mean "hosta la vista baby," but it sure makes them look like they were in a gunfight.
Try to keep leaves as dry as possible by using soaker hoses or watering the soil rather than the plants. Improve air circulation as much as possible by dividing plants or selectively thinning trees. If anthracnose still seems to be a problem, it may be worth beginning a fungicide spray to protect the emerging leaves. Ideally fungicide application should begin in spring as new leaves emerge and as long as wet weather continues. Look for fungicides containing thiophanate methyl as the active ingredient. Always read and follow pesticide label directions. Check to see that the fungicide is labeled for hosta to control anthracnose or leaf diseases.
Although more common in southern states, Sclerotium blight can be a serious disease of hostas. Symptoms first appear as lower leaves wilt and brown. Eventually upper leaves wilt and show a soft, brown rot of the base of petioles. This disease is difficult to control since the fungus can reside in the soil.
As for the holes in the leaves, I suspect slug or snail damage. These are night feeders so go outside after dark and check for these pests with a flashlight. They typically leave a slime trail. If you find them, hand pick and remove from your garden or try controlling them with Sluggo or other slug and snail control products.
Good luck with your hostas!