Peach leaf curl

Anthracnose

This week's highlights -- or lowlights

By John Fulton

[May 22, 2013]  What a difference a year makes! Last year we were warm and dry for large parts of the spring, and this year has been cool and damp for the most part. With the type of weather we have experienced, it should have been expected that many different diseases would come our way this spring. Well, they are here. Here are some shorts on the past week and some of the diseases found without looking too hard.

Peach leaf curl is caused by a fungus on trees in the stone fruit family. This would include mainly peaches and plums. It is rather striking with the bright red swellings on the green leaves. This disease can only be prevented with a dormant-time application of a fungicide on your trees. Seeing it now means that you probably should have sprayed before the buds began to swell (meaning before leaves actually came out).

Anthracnose starts as dead areas between leaf veins or on the tips of leaves. When severe enough, leaves will fall. Several of the infected trees have actually had the leaves turn completely black already. On many trees, it is much more noticeable on one side, due to air movement carrying the disease and drying out foliage quickly. The good news is that it rarely harms trees. If enough leaves drop, a new set comes out in four to six weeks and we start all over. The next set of leaves may also get the disease, but they may not. Infection can continue with weather favorable to the disease and when nighttime temperatures stay under 65 degrees. Treatments when you see the symptoms of this disease are simply wasted time and money.

Apple scab, a disease similar to anthracnose, can cause premature leaf drop in apples and crabapples. If you are on a regular spray schedule for fruit trees, it should prevent most of the problems. You could also spray crabapples this way, but you would have to weigh the cost and benefit since no fruit production is involved.

As a reminder, spray programs for disease prevention in fruit trees should be applied every 10-14 days after the bloom period is over. It should be stressed that these are preventive programs and not curative. These programs then continue until roughly two weeks before the fruit is ready to harvest.

Garden update

Just to catch up on a few things, we are now ready for the warm-loving vegetables to be planted. This would include lima beans, cucumbers, eggplant, melons, sweet potato slips, and summer and winter squash. You would want to accomplish these plantings around June 1 at the latest for summer harvests.

In another two weeks or so, we'll begin planting for fall garden harvests already, with plants such as potatoes, summer squash and tomatoes.

You can also do second-crop planting of sweet corn, green beans and cucumbers. Just remember, the length of time between your first and second plantings will not equal the time between the harvests. Heat units and length of night affect the crops. Heat units accumulate much faster during the summer months, and the length of night will be equal on either side of the summer solstice.

[By JOHN FULTON, University of Illinois Extension]