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I've been told to follow up an infestation of apple scab by composting any leaf litter on the orchard floor to destroy spores. I plan to haul away most of the leaves to my garden composter but a 5% urea solution is indicated for the orchard floor. How much should I need per mature tree (10 ft diameter drip line) and are there any safety concerns with preparing the solution in a sprayer tank?

I figure 5% urea solution is about 2 lbs (pounds) urea in 5 gallons. It comes from my coop in 50 lb bags of prills.

Lorem Ipsum
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Erik Olson
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1 Answers1

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According to UMass, you should spray 100 gallons per acre, or .00229568 gallons per square foot. A 10' diameter circle is 78.5 square feet, thus requiring .18 gallons. If you make one gallon of solution, you can treat 5 mature trees.

If you have the trees planted in rows in an orchard, the orchard will cover more space than just adding up the trees. (E.g. 10 trees in two rows of five with a uniform 10' spacing will use more than 785 square feet of space.) This is because of the gaps between the circles -- and you'll want to treat those gaps as well.

A 50 lb bag of urea will make about 125 gallons of solution, or enough to treat 1.25 acres of orchard.

Note that the article linked above suggests the use of feed grade urea as it dissolves better.

I'm not qualified to comment on the safety aspect.

bstpierre
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