The other day I was hanging out in my potato patch, just watching lady beetle larvae crawl all over the place. I turned over a leaf and saw this:
The photo isn’t very good, and it’s hard to describe what’s going on in it, but it seemed like there were ants crawling all over a couple of small, brownish, strangely-shaped crusty things. When I went to touch one of the crusty things, it moved away from me. It scooted sideways around the stem like a squirrel around a tree trunk. I grabbed it and pulled it off and the ants acted more frantic than usual, which is saying something. They kept scurrying around the spot where the thing had been, like they were looking for it.
The brownish crusty things are leafhopper nymphs. While the nymphs scurry instead of hop, the adult leafhoppers live up to their name. When disturbed, they spring up and away and are hard to catch.
The problem with leafhoppers is they pierce the plant with their mouthparts, injecting saliva, which plugs up the vascular tissue causing damage. The tip of the leaves begin to turn yellow and curl. This appearance is called “hopperburn.” It can stunt growth, cause shortened internodes (the space between leaves on a stem) and cause fewer blossoms. At its worst, it can kill a plant.
What about the ants? The ants, it seems, are “farming” the leafhopper nymphs. They protect them from predators, move them around when they feel the need, all to feed off a sweet substance exuded by the nymphs, called honeydew.
What to do? As an organic gardener, my first step is to watch and wait. A few leafhoppers won’t kill my entire potato crop. I’m picking off nymphs I find and will keep a lookout for signs of hopperburn. Kaolin clay sprays (like Surround) and diatomaceous earth have been suggested for control, but I won’t spray unless I think it’s getting out of hand. Those controls can also harm beneficial insects, so I don’t want to meddle unless I think it’s absolutely necessary.
Anyone have experience with leafhoppers on their vegetable or fruit crops?
On a positive note, aren’t potato blossoms pretty? And they smell so good, too. (I keep expecting the flowers to smell like potatoes so they smell extra nice to me when they don’t).