The start of the growing season, when the test was performed, was a good time to fertilize (we're not sure why they included that specific of a timeline), but you can apply fertilizer next spring. A reduction in fruit yield can be due to a range of factors, and soil fertility alone probably was not the reason for poor fruit set. For example, insufficient pollination back during our rainy spring, or a late frost, might have been key factors. Plus, if the trees have only been in the ground 3 years or less, they should not be fruiting heavily yet, as that's a big energy drain on a young tree that is still establishing. Ideally, all fruits that form should be removed while still small on a tree that's been in the ground only two or three years, and it can be allowed to fruit normally after that point. If a young tree was fruiting for its first couple of years in the ground, that drain on its resources may explain why fruiting declined lately, since it needs to recoup some energy reserves. Some cultivars are more prone to "alternate bearing" than others, which means that heavy fruiting one year will result in poor fruiting the next, and it goes back and forth from one to the other unless a heavy crop is thinned enough early in the fruit development process. Information about that can be found in the fruit pages below where it's relevant.

You can find care recommendations for fruit trees both in our fruit pages pertaining to individual crops (some related fruits are grouped together, like pears with apples, and cherries with plums), as well as the pages below. Pawpaw is still uncommonly grown for fruit, so while we do have information about its cultivation in the Less Common Fruits page, it's a little less extensive than the other fruit types. Pawpaw generally does not need supplemental fertilization, though it might help to boost fruit production a bit compared to wild trees not being grown specifically for a harvest.

• Fruit Plant Care (which includes general tips for fertilization)
• Understanding Your Soil Test Report (in case there are aspects of the results that are in question)

Miri

Thanks so much, Miri, for your response with such clear information! I’m learning a lot about fruit trees and will pass this along to our team at Stillmeadow Peace Park in Baltimore city.

Should we fertilize before the trees blossom or is that not a factor? I’ve read various recommendations about timing for blooming and fertilizing.

Thanks again.
Blessings,

Mary Jo 

You're welcome!
If the pages we linked to don't specify, then you can fertilize around the time of bloom if you want; the precise timing is not critical, and (for organic fertilizer ingredients at least) it will take some time for soil microbes to make those nutrients available to the roots, so impacts won't be immediate.

Miri