Brown rot on sour cherry trees
I have had major brown rot on my 2 Meteor cherry trees for 4 years now and have tried all simple measures of pruning and cultivation and some spraying. I now need some better advice for a sustained campaign against this. Can you please suggest which fungicides to use and where to buy them (since Bachmann's and other garden stores do not carry a range). I am interested in whether there are any systemic treatments I can do around the roots, or is all about spraying the leaves etc. I know some details about resistance - but rather than a smorgesbord of possibilities, I would like a simple plan of action and some brand names. I have a garden hose spray can system already. But I would like to know - week 1 use this, week 2 use that, when/where to use oil or copper etc. The advice from garden centers that I have been getting has been inconsistent and usually not very well-informed, but there is too much information to process when I go online.
There are two different brown rots
American brown rot
European brown rot
American brown rot is more common but Meteor gets European brown rot easily.
The Michigan recommendation is to prune out shoot strikes in the dormant season and spray with a material containing fenbuconazole. Fenbuconazole is the only effective material that is available to the home owner in Spectracide Multi-Purpose Fungicide. There are several different formulations of Spectracide which is a brand name product line so be sure you get the right material. Check the label for ingredients. The first spray should be put on at the popcorn stage just before the flowers open. Another spray at bloom or whenever you get a warm rain will reduce infections.
If you have fruit rots you have American brown rot and the same material should be used as the fruit colors to red whenever it rains during harvest.
Thank you for your advice. However, I cannot find this product at all. The Spectracide product I can find is called immunox multipurpose and it is based on Myclobutanil and Ethyl-3-ethoxypropionate. I see that INDAR 2F (and ENABLE and IMPALA) from DOW have the ingredient - but they seem to come in ton volumes. I have checked the CAS number (114369-43-6) and all the rest of the confusing names it can have (seem to find butyronitrile coming up a lot), but I cannot find any product I could buy anywhere with this. By the way - it is American Brown Rot and is so far only destroying the fruit not the blossoms, although some of the branches get a little shrivelled - but plenty new ones come up. But I basically lose all the fruit every year.
OK, even though myclobutanil and fenbuconazole have the same mode of action their activity on brown rot is different. Myclobutanil is an excellent material to use for the blossom rot phase of the disease so you can use it during bloom and immediately after until there are not petals left on the tree. You do need an infection period of rain during bloom and the average temperature during the rain needs to be above 50. I also recommend materials containing chlorothalonil just before bloom Chlorothalonil is a good protectant material that needs to be applied before a rain. You will also need to protect the fruit from American Brown rot during the ripening period when you have all your problems. You should spray the fruit as it starts to ripen and you should do it every 10 to 14 days. Ten days if it rains and 14 if it doesn't.
I see part of my answer disappeared.
You cannot use chlorothalonil after the fruit emerge from the shuck!
I recommend you use Bonide Fruit Tree and Plant Guard Concentrate after bloom. This is a homeowner tree fruit mix containing an insecticide and two fungicides. These mixes are used for cover sprays after bloom when you want to control both insects and diseases. Cherries in the Midwest are attacked as the ripen by cherry fruit fly and the spotted winged drosophilia (SWD) as well as being susceptible to the fruit rot phase of the disease. Start spraying after all the fruit are yellow.