Q.My plum tree leaves are turning red
My plum tree leaves are turning red. One is completely red and dropping and the other one is just starting to turn red. I saw a couple of leaves on the ground. My soil is sandy loam and we had 15″ above normal rainfall by the end of June. It hasn’t rained since and is dry. The leaves aren’t curling but some kind of insect has eaten holes in them.
It could be phytophora root rot. This would cause dropping red leaves en masse. For more information on phytophora root rot, please visit the following extension article (PDF):
It may also be a nitrogen deficiency. A severe nitrogen deficiency can make the leaves red and yellow and prone to fall off. A soil test will help you determine this - more information on soil tests can be found here:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
