A Technical Report from The Bartlett Tree Research Laboratories
Phytophthora root disease is a widespread but often overlooked disease of landscape plants. There are many species in this genus that attack woody ornamentals. These fungus-like organisms grow in the fine roots, cambium, and sapwood causing death of the tissue, root rot, and collar rot. Loss of water and nutrient absorbing capacity and stored carbohydrate reserves in the root cause a decline of the above-ground portion of the plant. Phytophthora diseases are most common on soils that are poorly drained or receive excessive irrigation. Phytophthora is a soil-borne organism that forms resting spores that can survive long periods without a host. When soil moisture and temperature conditions favor disease development, Phytophthora can increase rapidly from undetectable levels to infestations.
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- I planted six young trees in early March. Despite watering them regularly they have all started to wilt and the leaves are starting to turn yellow.
- I planted an ornamental cherry tree in my front lawn and have noticed bleeding around the bottom part of the trunk. This season it bloomed and I noticed a considerable reduction in the amount of leaves. Is there a problem?
- I believe two of my large vine maples (planted two years ago) are dying of root rot. They both have collar lesions. There are three others in the vicinity. I have read up on Phytophthora and know the basics. Is it likely to spread to the other three? Is it important to remove the dying ones immediately? Is there an effective treatment for the remaining three?
- I have two horse chestnut trees, which are approx 25 years old. This year, the leaves started to discolour in the summer and now red liquid is coming from the bark. Is there any cure for this disease or do I have to destroy them?
- We planed the tree in the fall, following instruction from the grower, but there are several branches towards the bottom of the tree showing signs of browning. Is there anything we can do. We have had a very wet winter and spring so I'm worried the water is not draining well. Could this be the problem?
- Our 13 year old Rhodedendrons in front of the house have slowly been dying over the past three years. We tried feeding, watering, and spraying with milky substance for a bacterial infection with no results. The leaves turn brown on tips and curl. The tops of leaves are pale in color with veins remaining a darker green. The underside of leaves have tiny rusty/brown colored dots. What should I do?