Question
Some of my hackberry trees have leaves curling down & dying.  One (10" trunk)has 90% leaf loss while beside it (25" trunk d)has about 1%.  And another (1/2" trunk size Has 50%.  They all have 'scale insects which county agent didn't think would affect the trees at this stage.  We had some late cold weather. ??  Also drove by them with a sprayer full of 2-4-6 mix but did not spray within 1/4 mile.  Any ideas??

Answer
Dear Nelva, This is a very difficult question, and one with no easy answer, and I wish I were able to take a look at the trees personally.  However, even then I might not be sure, since this is actually an unusual situation.  One obvious possibility would be drought.  Even if your trees are not in a drought situation this year, how did they fare last year during the severe drought across most of the US?  (My area of Texas was hit hard.)  That could cause the leaf problems, but it would be more likely that they would fail to leaf out.  Ordinarily I would suggest that borers could be a problem, but you would have to have some desperate borers to attack a hackberry since the wood is so hard.  But look for holes around the trunk and loose bark and if you suspect borers you could spray with spinosad.  Ok the scale is weird, and if the problem is scale, then you should spray with a horticultural oil or biorganic oil to smother the scale and you would have to spray them several times to get rid of it.  I don't know why you would have scale on hackberry trees.  However, if you do, then absolutely get that under control.  One other thing that occurred to me is that perhaps it has a fungal infection.  You could spray the trees with NEEM (which kills insects, fungus and mites) mixed with horticultural oil for the scale and the trees should start to look better.  Now if when driving by the trees with the herbicide, the equipment was leaking and the wind was blowing, you could have given them some spray accidentally.  A quarter mile would be a stretch for spray drift and would really only happen if the wind was blowing hard in which case I doubt you would be spraying.  So, I am not sure what is wrong with your trees, but rule out drought and borers, then I would probably spray with NEEM and horticultural oil for the scale and your trees should recover.  Good luck and if you do get a diagnosis or if this treatment works, please let me know.  Melissa