Tuesday, August 17, 2021

x
Tuesday 17 August 2021:
News Briefs
  • The Wyoming County Fair Ends this Saturday. The Daily News invites you to enjoy this rainy clip from the Fair:
  • 4 1/2 foot long Nile Monitor Lizard remains missing in Village of Attica. It escaped from its cage last week and so far has alluded capture.
  • August weather, gypsy moths and dropping leaves creating maple tree woes -- Guidance offered by The Daily News

Saforrest | GNU Free Documentation License & Creative Commons Attribution-Share Alike 3.0 Unported Tar spot fungi overwinter on fallen, infected leaves. They produce spores the following spring. As trees start to leaf out, the needlelike spores are discharged from the black spots. Spores are then dispersed by the wind. If spores land on young maple leaves, they can germinate, enter the leaf tissue and the disease starts over. Moisture is necessary for the spores to infect the leaves.

It’s been a tough year for some trees. Whacky weather, no rain, too much rain, gypsy moths and now maple trees are dropping leaves — in August. If you drive around Batavia, you’ll notice that a lot of maple trees are losing leaves, some more than others, even on the same street. Normally we would suspect tar spot. This year not only are we seeing tar spot, but some trees also have anthracnose. Both are fungal diseases that affect maple trees.


Tar spot is caused by several different fungi in the genus Rhytisma. The first symptoms are tiny, pale-yellow spots which appear in spring or early summer. The yellow spots grow to an inch or more over the summer. On red and silver maple, a black spot usually develops in each yellow spot by mid-July to early August. By late summer the black spot has developed into the noticeable tar spot and the leaf may turn brown. Individual leaves can have multiple tar spots.

Tar spot fungi overwinter on fallen, infected leaves. They produce spores the following spring. As trees start to leaf out, the needlelike spores are discharged from the black spots. Spores are then dispersed by the wind. If spores land on young maple leaves, they can germinate, enter the leaf tissue and the disease starts over. Moisture is necessary for the spores to infect the leaves.

Maple anthracnose is caused by several different, but related fungal pathogens. Unfortunately, all our native maples as well as non-native maples are susceptible to infection. Usually, we see anthracnose on maple in spring or early summer. Like tar spot, it tends to be more of an aesthetic issue. While symptoms vary by host, look for large, irregularly shaped, angular blotches of dead tissue mainly along the leaf margins and veins. Leaves tend to be curled or distorted. Anthracnose typically begins on leaves in the lower branches and moves up. Anthracnose can also create cankers on twigs which can result in dieback of young shoots.

Anthracnose fungi overwinter on fallen leaves, plus infected buds and twigs. Spores are produced during mild and wet conditions from spring through late summer. They are spread by wind and splashing rain. Make a note of which trees get anthracnose as it tends to occur on the same trees annually. If it becomes severe enough fungicide treatment may be warranted.

Usually neither tar spot nor anthracnose is likely to damage a healthy tree, but a heavy infection of either one, can cause leaves to fall off early. Tar spot usually happens late enough in the season so that tree growth is not affected. If anthracnose happens early in the season and defoliates the tree, it will likely re-leaf.

What should you do if your maple trees have tar spot and/or anthracnose this summer? Sanitation is probably the most important thing you can do to decrease the severity of both diseases next year. The best thing to do is to rake up the leaves and destroy them or get rid of them. Encourage your neighbors with maples to do the same. Good sanitation will reduce the number of overwintering fungal bodies which produce the spores. Fewer spores next spring means less chance trees will become infected.

Since both diseases tend to be mainly an aesthetic issue, using a fungicide is usually not recommended. Applying fungicides after the symptoms appear will not control or cure either disease. Leaves need to be completely covered with the fungicide and this can be hard to do on large maples. If your neighbors do not treat their trees with fungicides or clean up their leaves, spraying your trees will be a waste of time and money. As the spores are wind borne, they can easily travel throughout the neighborhood. If you decide to use fungicides, you may need to spray almost every year depending on the spring weather conditions.

There are some cases when using a fungicide might be necessary. Younger, smaller trees may need fungicide protection to prevent defoliation which would be detrimental to the tree. You might want to spray trees that have been stressed for several years by gypsy moths or are suffering from other diseases. This would be something to consider for next spring as you want to protect new growth from infection. Available fungicides are preventive, not curative, and must be applied before infection occurs.

If you do use a fungicide, be sure to read and follow the label directions as well as the safety precautions. Select a fungicide that is labeled for the disease and the plant that you are using it on (i.e., maple) or reach out to a certified arborist to treat your trees.

Keeping your maple trees healthy will help minimize the impact these two diseases can have. Mature, well-established, healthy trees should be able to tolerate tar spot and anthracnose without long term affects. Cultural methods such as mulching, proper watering and fertilizing can help. Trees need an inch of water per week, so watering may be necessary during extended dry periods. Remove damaged, dead, or diseased branches properly. Heathy trees are resilient, but they are certainly being challenged this year.

Resources for this article include Cornell University, University of Minnesota, Iowa State University, University of Wisconsin, Michigan State University, Purdue University and University of Massachusetts.

master gardener training

Have a gardening question? Master Gardener volunteers are normally in the office Monday through Friday, from 10 am until Noon. You can stop in at our CCE office at 420 East Main Street, Batavia, call 585-343-3040, ext. 127, or e-mail them at: geneseemg@hotmail.com. Visit our CCE web site at genesee.cce.cornell.edu or like us on Facebook www.facebook.com/CCEofGenesee.

CCE Genesee will offer Master Gardener training this fall. Classes will be Tuesday evs from 6 to 9 p.m., starting Sept. 7 and running through Nov. 16. There will be a full day of classes on Oct. 23 (9 a.m. to 4 p.m.). Pre-registration by Aug. 24 is required. Class size will be limited. The fee is $225 per person. We are planning to hold classes in-person at the CCE Genesee office, 420 E. Main St., Batavia. Contact Jan Beglinger at 585-343-3040 ext. 132 for information.

A year in the garden

Join us for Garden Talk on Sept. 2. This free program will be held on Zoom and will start at noon. The topic will be “A Year in the Life of a Garden.” Gardens aren’t static, they change as we progress through the seasons, even over the years. Join Master Gardener Lynette to see how the plantings change in her small city garden from spring to winter and year to year. Please register at our CCE website events page genesee.cce.cornell.edu/ to get your link.

No comments:

Post a Comment