I have a mature plum tree and I have just noticed that it is infested with ants. It looks like they are in around the trees roots and they march up and down into the tree through holes in the trunk. Around each of the holes is fine brown gritty sandy stuff. What are they doing? and should I be worried and trying to do something about it?
They are gathering at the bottom of your tree where they are planning an assault your tree in conjunction with the aphids that they ally themselves with. Both will multiply rapidly the ants distributing and farming the aphid and the aphids feeding off your new tender tips of your tree. What works well is a product called tangle foot its a sticky substance like soft gum. You spread it around the trunk about 4-5" wide creating a barrier that if the ants try to cross they get stuck in. After a short time they will retreat to find other food sources. I am using duct tape with a thin layer of axle grease on the top. It work well as a deterrent and when the ants move on you can dispose of the tape.
The ants, if they are excavating into the trunk, may have found moist rotten wood in there ("heart rot") initiated by one of several causes including canker-type disease (common name "European Canker" round here - probably not scientifically correct). This gives them great nesting sites close to their herd of aphids, which they are milking. I have removed over the years, all the fruit trees (apple, pear, plum, cherry) from my lot, 'cos I am lazy & can't be bothered dealing with the disease problems in the Fraser Valley. Your symptoms remind me of the reasons I removed my Quince (true Quince - not Japanese) which I greatly miss. It was about 25 years old from a cutting which was probably infected with canker from it's parent. If I were to do fruit trees again, I would plant new every ones every 5-10 years & just remove the older ones when they start to seriously deteriorate after 20 years or so. Meantime I can buy wonderful varieties of fruit from the local orchards, where they actually know what they are doing & are diligent! My suggestion: Nurse this one along. Plant another after investigating disease resistance. Once the new one comes along, remove the old...of course by that time, the old one will have infected the new one with heart-rot, brown rot, european canker, leaf roll, little fruit, tent caterpillars, diptheria, measles & the common cold. Maybe we could get our trees vaccinated when they are young, just like our kids & pets? BTW I am definitely not a fruit tree expert. They are out there...at UBC & specialist orchards. gb
Thanks, I don't actually like the Plum tree. I don't eat the plums, it attracts racoons, they are a pain to clean up when they drop, but the tree is mature and I want it to live as long as it can becuase of that reason. Will give the tangle foot a try.
I know. The spring flowers & foliage on the fruit trees are glorious. I think if you spray the foliage with a hose - full pressure jet - & knock off the aphids, the ants will be controlled as well. Try using "Borax & Molasses" ant poison as well in the holes where the ants are excavating. I do not believe that this preparation will harm the tree if pasted on the bark & in contact with the heartwood. It works well on ant nests, but requires patience since the Borax works on the larvae. gb
We've removed 2 mature plum trees in the last few years, and were amazed to discover ants up & down the middle 2-3", the length of the trunks. I always knew we had lots of ants, but apparently my plum trees were making great anthills? Perhaps more amazing was that one of the trees appeared quite healthy. The other had clearly been weakened by it's insides being turned to sawdust (gee, you think?) and split in half under a heavy snow load a few years back. It was so badly off, my husband was able to knock the rest of it over with a good swift kick. If you can see that many ants, holes, and evidence of sawdust, maybe you should just take it out before it falls over. Thanks for the reminder to be vigilant with my new trees!
