# Ohio Disease Report



## treeseer (May 18, 2006)

You Ohio guys get this newsletter?

Buckeye Yard and Garden Line (BYGL). 
BYGL is available via email, contact Cheryl Fischnich [email protected] to subscribe. Additional Factsheet information on any of these articles may be found through the OSU fact sheet database [ http://plantfacts.osu.edu/ ].

BYGL is a service of OSU Extension and is aided by major support from the ONLA (Ohio Nursery and Landscape Association) http://onla.org/ and http://buckeyegardening.com/ to the OSU Extension Nursery, Landscape, and Turf Team (ENLTT). Any materials in this newsletter may be reproduced for educational purposes providing the source is credited.

BYGL is available online at: [ http://bygl.osu.edu ], a web site sponsored by the Ohio State University Department of Horticulture and Crop Sciences (HCS) as part of the "Horticulture in Virtual Perspective." The online version of BYGL has images associated with the articles and links to additional information.


It's got stuff like this; may be handy to know:

E. ANTHRACNOSE DISEASES OF SHADE TREES. Conditions earlier this Spring in some areas of Ohio were not particularly conducive to development of some of our common anthracnose diseases, such as ASH ANTHRACNOSE (Apiognomonia errabunda) and SYCAMORE ANTHRACNOSE (Apiognomonia veneta). Infections by the causal fungi are enhanced by cool, wet conditions during early leaf development, and drier areas of Ohio did not have these conditions until this past week. Nevertheless, enough earlier infections had already occurred, even in the drier areas, so that ash anthracnose and sycamore anthracnose was observed throughout Ohio this past week. With the prolonged cool, wet, cloudy monsoons we can expect much greater incidence of these diseases to show up in the coming week or two.

Look for grayish water-soaked appearances of leaves on both plants, with big blotches delimited by the center vein on ash and some total leaf blight and discoloration along main veins on sycamore leaves. On sycamore this may result in very sparse foliation and a good bit of twig dieback. On ash, look for considerable leaf drop, especially on the lower branches of the tree where higher moisture and relative humidity prevails. (see pictures of ash anthracnose at: http://plantfacts.osu.edu/pest/disp...n&-Table=html&-Database=Insects&-KeyValue=482 and sycamore anthracnose at http://plantfacts.osu.edu/pest/disp...&-Table=html&-Database=Insects&-KeyValue=4457 ). The good news is that, even with the large number of leaves on the ground with ash and with very sparse foliage on sycamores, these trees typically recover quite nicely and the problem will be largely forgotten by the end of June. Use of fungicides is rarely recommended. Fungicide applications would have had to be made at bud break to be effective. See the OSU Extension Factsheet on anthracnose at: http://ohioline.osu.edu/hyg-fact/3000/3048.html

F. APPLE SCAB ON CRABAPPLE. Our wet weather this past week is also the "environment conducive to disease" that helps lead to significant APPLE SCAB OF CRABAPPLE. Starting with lower leaf surfaces from spores splashed from overwintering fungal inoculum on last year’s scabby leaves and then occurring on upper leaf surfaces, scab is starting to show up on susceptible Malus taxa already, and presumably will be greatly enhanced in days and weeks to come due to our past week of wild wet weather. (for images of apple scab, visit http://plantfacts.osu.edu/pest/disp...&-Table=html&-Database=Insects&-KeyValue=4337 )
Fungicides to prevent scab will of course not get rid of these primary infections, but subsequent applications will help limit secondary infections as the season progresses. Of course it is difficult to even make applications while it keeps raining. For the OSU Extension factsheet on apple scab, visit http://ohioline.osu.edu/hyg-fact/3000/3003.html .

The best alternative for the future of course is to practice the ultimate in disease prevention: plant crabapples with good genetic resistance to infections by the scab fungus (Venturia inaequalis). There are many, from 'Red Jewel' to 'Strawberry Parfait', from 'Royal Raindrops to 'Sargent', from 'Bob White' to many of the Round Table Series. For an extensive list of our crabapple trials, connect to our OSU Extension research data from the Crablandia trials at OSU’s Secrest Arboretum at the Ohio Agricultural Research and Development Center. For more information on crabapple trials from the current Ornamental Circular, go to: http://woostercenter.osu.edu/SC197-05-13 Crab Knowldg.pdf


----------



## Rtom45 (May 23, 2006)

Thanks for the tip. I went to the plantfacts site and it seemed very useful - I bookmarked it.


----------

