Anthracnose (fungus)	Irregular brown to reddish spots develop between veins and along margins. Infected leaves turn yellow and drop prematurely.	Refer to the PDC Fact Sheet "Leaf Spot Diseases of Shade Trees and Ornamentals" for more information. Use chlorothalonil, copper products, mancozeb, maneb, myclobutanil, propiconazole, sulfur, thiophanate-methyl or triadimefon.
Black leaf spot (fungus)	Small, irregular spots that become shiny, tan to black and raised.	Refer to the PDC Fact Sheet "Leaf Spot Diseases of Shade Trees and Ornamentals" for more information. Some varieties have resistance. (See resistant varieties.) Mancozeb may be used.
Dutch elm disease (fungus)
Initially, infected trees have scattered dead branches. Brown streaks in sapwood.	Leaves wilt, turn yellow and brown. Terminal parts of tree affected first and later the entire tree. Brown discoloration occurs in sapwood just under bark in wilting branches. Positive identification requires laboratory culturing. Send specimens to the Extension Plant Diagnostic Clinic. Flagging of leaves on affected branch. Fungicide injection.	There is no control for Dutch elm disease once the infection reaches the trunk and roots. At present, control consists of the following preventive steps: 1. Sanitation: remove dead and dying elms that serve as breeding sites for the insect vec tor. 2. Sever root grafts with metam sodium (sold as Vapam) or by mechanical means. Dutch elm disease can be transmitted from a diseased elm to an adjacent healthy tree through root grafts. 3. Therapy for infected trees is questionable. Therapeutic fungicide injection is only effective if less than 5% of the crown is symptomatic and not at all effective if the trees are infected through a root graft. Use of a fungicide-injection program is most beneficial to protect valuable specimen trees. Use copper sulfate pentahydrate (Phyton 27), debacarb (Fungisol) or propiconizole (Alamo), thiabendazole (Arbotech). Some hybrids and cultivars are resistant.
Elm leaf beetle larvae feeding	Lower surface of the leaf between the main veins is chewed off. Smaller veins remain intact. Damaged areas become brown.	See MU publication G 7356
Elm yellows (Elm phloem necrosis) (phytoplasma)	Formerly called elm phloem necrosis. During June and July, leaves roll upward, turn yellow or brown, wither and drop pre maturely. Death of tree is fairly rapid. Inner bark near trunk base is yellow to butterscotch colored.	Infected trees cannot be cured. Use vec tor control for leafhoppers. In localities where elm yellows is active, plant resistant or tolerant hybrids.
Wetwood or slime flux (bacterium)	Sap flows from branch stubs, split crotches, trunk cracks or other bark wounds. When slime flux occurs, sap ferments, foams and bubbles.	No control recommended.
University Outreach and Extension does not endorse commercial products. Follow the label on all pesticides.

[ Top of Page ] [ Back to Index ]
	Email: plantclinic@missouri.edu