Verticillium Wilt Treatment – Acer Tree

Question

We have an Acer tree that started developing symptoms of wilt last summer; the same symptoms are repeating this year with the leaves on whole branches drying up, curling and dying, while leaves on other branches remain healthy. I have attached three photos showing the problem. Having discussed matters with a landscape gardening we know well, he felt the tree was suffering from Verticullium Wilt. On your website, page https://www.gardeningknowhow.com/plant-problems/disease/verticillium-wilt-treatment.htm under the section headed Control (of Verticillium Wilt), it says “Fertilize on schedule, using a low-nitrogen, high-phosphorus fertilizer” However, on RHS’s website, page, https://www.rhs.org.uk/advice/profile?pid=255 under the section headed Non-Chemical Control, it says “apply a nitrogenous fertiliser to the root spread; use sulphate of ammonia at 25g per sq m (1oz per sq yd)….. once or twice during the remainder of the growing season”. Are these two pieces of advice contradicting each other. i.e. (1) using a low-nitrogen (high phosphorous) fertilizer and (2) applying a apply a nitrogenous fertiliser to the root spread? Yesterday I bought and applied Westland Sulphate of Ammonia and am now wondering if I have done the right thing. Many thanks, Ian

• 
• 
• 

Answer 1

This information is quite contradictory. I would not advise high nitrogen in this situation. Only enough to feed the tree, but focusing more on phosphorus and potassium is advised. Since there is no registered chemical control (rather, there is no EFFECTIVE chemical control) it is best to use preventative maintenance to care for the tree.

This will consist of keeping every single leaf or scrap that falls swept up and burned or disposed of properly, and keeping any heavily infected growth pruned away and disposed of.

Here is a link for more information:

https://ag.umass.edu/landscape/fact-sheets/verticillium-wilt