Boxwood Insect Damage

This is a special edition of our newsletter focused on boxwoods. In all situations below, fertilize damaged plants in fall and spring. Water regularly and deeply during drought periods.

If you would like assistance in determining your situation, please bring photos of the plant and a small sample of your plant in a sandwich baggie with you to the store.

Spider Mite –

Mites feed by sucking the sap from leaves, leaving tiny spots on leaf surfaces.  Leaves may look pale from many tiny wounds.  Prevalent in hot, dry conditions when plants are stressed.  Most damage is done in the spring.  Whitish/yellowish eggs are laid in September and October and hatch in mid spring.  They are barely visible to the human eye.  New growth is most susceptible.  Test for spider mites by placing a white piece of paper under a branch and slap it on the paper.  Look for tiny moving dots. 

Treat with insecticidal soap, horticultural oil, Malathion, or Bonide Fruit Tree and Plant Guard.  (Not all insecticides will control mites.)  Spray 10 to 14 days apart in spring.  Spray as needed during the summer.  Spray again the following spring.

Leaf Miner –

Look for tiny gnats flying around in spring.  There is 1 generation per year.  Eggs are laid between the top and bottom leaf surfaces.  As the eggs hatch, they leave blisters visible on the underside of the leaf.

Trim boxwood tips in spring before new growth appears to prevent overwintering eggs from hatching.  Clean up trimmings and dispose.  Spray when leaves are fully formed – late April to early May.  Make a second application between mid-June and mid-July.  Spray with Captain Jack’s Dead Bug Brew, horticultural oil, or insecticidal soap which are all organic.   Apply to the entire leaf surfaces, top and bottom.  Imdacloprid can be used as a chemical systemic soil drench which is effective for one year. 

For severe cases prune affected branches.  Dispose in trash.

Psyllid –

Cupped or curled leaves on the new growth are the symptom of Psyllid damage.  Leaves may turn yellow.  Small green sucking insects create fluffy white waxy secretions at the tips of new growth as it emerges in April – May.  Prune out and destroy affected tips before adults emerge in early summer (late May to early June).  The adults lay eggs in the bud scales in June and July.

Spray with Captain Jack’s Dead Bug Brew (Spinosad – organic), neem oil, insecticidal soap, or horticultural oil in spring as new growth occurs.  These are organic methods.  (Spraying before or after is not as effective.)  Imidacloprid can be used as a chemical systemic soil drench which is effective for one year. 

Huntree Nursery                   269-543-3761

Categorised in: Newsletter

This post was written by MHarrison9