I assume many questions I get these days regarding citrus issues are from new listeners or Facebook followers, because their problems are mostly with leaf miners, and that’s a topic that has been covered extensively in my weekly tips and books. But, since I’m getting so many inquiries, I guess it’s time for an update on the pests.
Many questions are along the lines of, “Randy, what’s wrong with my (any citrus)? The leaves are all curling up and look shriveled.” Often, they’ll note “squiggly lines in the leaves.”
That’s a sure sign of citrus leaf miners, insects that are relatively new to the Houston area — the problem originated in Florida in 1993 and came here around 1995.
A homemade regimen is the solution, and I can assure you it works. Simply alternate neem oil and spinosad.
When I saw the first infestation of leaf miners on one of my satsumas, I immediately started the simple weekly control on all my citrus trees - lemon, lime, and satsuma - and I haven't had a problem since. But you’ve got to catch them early, before the infestation blows up and gets out of control.
However, if you missed the early control period in March, April and May, you can still attack them now through August if necessary.
So, we spray one of the two products, wait 7-10 days, then spray the other. And you do that for at least 8 weeks. One you start, you must CONTINUE the process for 8-10 total applications. You can also stop once temperatures go below 85 degrees for an extended period. In Houston, that’s typically in November.
If you don't have an infestation, it has been noted that you can do the alternating application as a preventive.
The moths that lay the leaf miners love new growth, so that’s what needs the treatment. If you spread out curled-up leaves, you’ll see "snack trails." Highly infected leaves can be pinched off.
The good news is that, while they can make leaves look ugly, leaf miners are usually not life-threatening.
By the way, I know there’s a warning on spinosad labels that caution against using it more than three times in a season. But because you’ll be alternating with neem oil, the insects won’t become accustomed to just one insecticide.
Neem oil and spinosad are both organically derived products and safe for fruit-bearing crops. I’m not comfortable with recommending any systemic chemical controls for citrus trees. Cygon, the one that was approved for fruit crops, is no longer available on the retail market.
PHOTOS: Left - Getty Images; Right - Stephanie Iha