Monday, July 27, 2015

Featured Diagnosis: Leafhoppers.

A sycamore tree with yellow leaves
Sycamore (Platanus sp.) tree exhibiting classic
"hopper-burn" symptom caused by leafhopper
 feeding. (Photo: NMSU-PDC)
Featured Diagnosis: Leafhoppers.  A number of sycamore (Platanus sp.) samples have been submitted to the plant diagnostic clinic with “hopper-burn” caused by leafhopper feeding. There are several species of Erythroneura that could be called ‘sycamore leafhoppers.’ These pests are whitish-yellow and about 1/8” long. Leafhoppers have piercing-sucking mouthparts and cause damage to leaves by piercing the foliage, sucking sap and leaving very tiny white dots on foliage where their mouthparts were inserted. The resulting damage appears as a white to yellowish-brown stippling of the leaves. Damage can be so extensive that injured leaves appear nearly white. Initially, feeding tends to be concentrated near the midrib, and then eventually covers most of the interveinal spaces of the leaf blade. Like other types of foliar damage, that caused by leafhoppers may reduce leaf photosynthesis which reduces the amount of carbohydrates produced and stored by the tree, ultimately decreasing vigor. Severe damage over multiple seasons could eventually reduce the tree's carbohydrate reserves, making effects of feeding damage more apparent. As with other indirect pest damage, factors such as tree vigor, tree age, drought stress, and damage by multiple pests could exacerbate the effect of leafhopper damage. Control of leafhoppers involves the application of a well-timed topical insecticide in the spring and as need throughout the growing season to keep the populations under control. 

A composite photo of two leaves with small yellow spots from leafhopper feeding
Leaf stippling or "hopper-burn" caused by leafhopper feeding.
Early symptoms left and advanced symptoms right. (Photo: NMSU-PDC)

The underside of a leaf with red arrows pointing to leafhoppers
Leafhoppers (Erythroneura sp.) feeding on the underside of a sycamore leaf.
These insects are
 whitish-yellow and about 1/8” long. (Photo: NMSU-PDC)

A composite of three images of leafhopper insects
Dissecting microscope image of Erythroneura leafhoppers.
Note the piercing mouthparts top right. 
(Photo: NMSU-PDC)

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