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Thursday, May 8, 2014

Leaf Cupping Normally Aphids...But Not This Time!

Q. My Blenheim apricot tree planted in 2012 is not doing well. A few branches have lost all their leaves. Other leaves are starting to curl and cup. This year it had plenty of apricots but few leaves. I thinned them out since the tree is young.

Note: Since this posting I have had numerous emails and pictures about a flurry of activity from stinkbugs in the valley. Stinkbugs are notorious for this kind of damage because there is not much to feed on early in the season and expanding buds/leaves are tender and juicy. I had to go out on this one and Andy spotted the critter before I did. Sometimes you just need an extra pair of eyes.

A. First thing I see in the picture you sent is that you have wood mulch. Please pull it back 12 inches from the trunk. The symptoms you sent to me could be damage to the trunk from wet mulch.
            Cupping is due to damage to leaf edges, not the entire leaf. The damage to leaf edges could be lack of water, salt damage, wind damage, damage from sprays or insects.
Leaf cupping due to damage to the leaf margins followed by expansive growth from the center outward.
            The lack of water could be either from a lack of applied water or damage to the trunk from wet mulch.
            Salt burn can be from applying fertilizer too close to the trunk or applying a heavy rate of fertilizers in the irrigation basin. Always keep fertilizer at least a foot from the trunk.
            It is best if the fertilizer is buried slightly in the soil or there is wood mulch present to keep the fertilizers from washing against the trunk after watering. Water the soil generously when applying fertilizers.
            When watering the fertilizer into the soil and you do not have wood mulch, try not to flood the basin around the tree. This can push fertilizers against the trunk and cause damage.  
            Even “hot” manures like chicken or other poultry manure can cause problems like this if they get too close to the tree trunk.
This stinkbug was not Andy's. This is from someone else down in Henderson area. Andy's was brown but looked the same otherwise.
            We have had quite a number of reports of stinkbugs in neighborhoods in Henderson and other places. Stinkbugs can cause feeding damage to leaves as they are expanding, causing leaf cupping. Look for stinkbugs on the trees and apply an appropriate insecticide if they are present in large numbers.
This is actually one of Andy's stinkbugs from last year. I am sure he died of old age. Not Andy, the stinkbug.

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