Q: I have a twenty-foot-tall ‘Candy’ pecan. There’s a large ‘Stuart’ nearby. Last year the branch tips died back and there were no pecans. They all turned black when small. Does this sound like scab or maybe a zinc deficiency?
A: A deficiency of zinc in the soil and in the leaves can certainly cause tip die-back but scab disease could cause nut drop too. Lack of zinc also causes rosettes of thin twigs at branch tips. Low zinc levels are not always a problem with pecans but you could treat the leaves with zinc sulfate solution now. It would be great to have the soil tested by the University of Georgia (georgiasoiltest.com) before you apply anything. It’s hard to find zinc sulfate at local nurseries so you may have to go online. Be sure to spray when the leaves are young: that’s the best time for zinc absorption. You can also apply zinc fertilizer to the soil for a longer term solution.