Leaf miner season

Anyone growing spinach or chard (or beets potentially too) should be on the look-out for leaf miner, that little maggot that burrows into the leafs creating little tunnels and eventually large dead splotches on the leaves. The miner is the larval stage of a fly and the adult fly is hard to control so focus on the eggs and larvae. Last year was a bad year for leaf miner and this year is shaping up to be another bad year for spinach.

leaf miner

leaf miner eggs on spinach (May 28, 2013)

leaf miner on spinach

leaf miner eggs
(close-up of left)

divider line

At this point the little buggers are already hatching and have started their work so people may want to exercise some controls:

  • check the undersides of the leaves for the eggs and rub them off or crush them (be careful not to damage the leaves) with your hands;
  • remove and discard well, not compost, any leaves that already have active leaf miners — or you can pop the larva inside the leaf with a little pressure ;-).
  • another easy option, especially for the squeamish, is to harvest all leaves that get to baby-size (say 2″-4″ long), since the really small, emerging leaves are unlikely to have eggs; done regularly, this will get rid of a lot of the eggs before they hatch.

If you let the leaf miner larvae get to maturity they will exit the leaf and drop to the ground, where they will pupate into flies and set off to lay more eggs later in the summer … for one more shot at your late-season crops.

leaf miner larvae

leaf miner larvae
(May 29, 2013)

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