Hi, My prune plum trees have plenty of fruit but, they drop almost all of there fruit before it is ripe. I was told that this was caused by a lack of water and iron in the soil. I have increase watering. I ordered a bag of ferrous sulpate to fertilize them but was told that this would kill the trees. Do they need an iron fertilizer? Is ferrous sulphate appropriate or is there another iron sulphate that can be used? Thank you.
Plums thin themselves and unfortunately most of the thinning is done as the fruit is ripening. Plums and Apples both will slough off fruit prematurely if there is not enough available Calcium to the tree. The effects of lack of Calcium will show up by us having the fruit drop sooner on occasion than we will see symptoms of a deficiency in the leaves. Two ways to prevent such massive fruit drop is to hand thin the trees ourselves starting soon after the fruit has become visible. One Plum per inch of twig and branch will serve as a good starting point. If you thin the tree right the first time you may not have to thin the tree again. The other is use a fertilizer with some Calcium in it such as a granular complete fertilizer such as a 12-12-12 that has about 6% Calcium in its formulation. Usually we do not apply iron sulfate to Plums unless the trees are showing signs of a noticeable chlorosis. We tend to use an iron chelate spray instead. I do not like to recommend a straight iron sulfate application by itself. I like to blend it in with another fertilizer such as Calcium nitrate and then add the mix into the soil. For Fruit trees we apply the fertilizer in a circle about 1 1/2 to 2 feet away from the trunk of the tree and then water the fertilizer in well. As a side note: For years here we used straight iron sulfate to lower the pH of our soil mediums such as ground based soils and to some extent potting soils (a must sometimes if we have alkaline water). An iron sulfate application by itself is not recommended for acid soils. I have provided two links below that deal with iron sulfate. http://extension.usu.edu/publica/agpubs/ironchlo.htm http://www.ext.colostate.edu/pubs/garden/07728.html Jim
I agree with Mr Shep, my plum trees do the same dropping of fruit. My five year old daughter suggested using glue to put them back on. I had to add this, I thought it funny ; ) Carol Ja
Listen to mr.shep. Ferrous sulphate will only make acid soil more acidic. A good place to start would be with your County Extension Office. Have Ph test run(typically three bucks here in Florida). That will give you a better idea of any amendments necessary for your particular soil. Gee, noticing your locale, I guess you don't have a County Extension Office. Sorry about that. Someone in your province has the governmental responsibility for testing soil for horticultrists and homeowners. Get a pint of soil to them for a Ph and soluable salts test. Good luck.
