Pests & Diseases

Milkweed Bugs

August 16 2017 RHR 041

Strolling in the garden at this time of year, you might be surprised to find your Asclepias spp. (milkweed) infested with orange- and black-spotted bugs. Often seen in groups of a dozen or more, they can be a shocking sight to gardeners. No need to worry: Oncopeltus fasciatus, the milkweed bug, causes minimal damage to plants.

This time of year, all stages of these insects’ lifecycles can be found on Asclepias seed pods.  Adults typically live a month during the summer, with females laying over 2,000 eggs in a lifetime. These eggs are placed in the milkweed seedpods or …

Continue reading »

Wool-sower gall

May 4 2017 RHR 107Some of the newly installed oaks on campus appear to have grown cotton balls with pink spots. These are actually a type of tree gall called Wool-sower gall.

This gall is produced by the harmless Cynipid gall wasp (Callirhytis seminator). photo credit: R. Robert

This gall is produced by the harmless Cynipid gall wasp (Callirhytis seminator). photo credit: R. Robert

This gall is produced by the harmless Cynipid gall wasp (Callirhytis seminator). These wasps lay their eggs on a specific plant and the eggs produce the grubs whose secretions cause the gall formation. The gall provides protection and nutrition. Their favorite host plants are oaks.

The galls do not harm the tree, …

Continue reading »

Cedar Quince Rust

April 21 2017 RHR 077This spring, orange goop appears to be taking over the Juniperus virginiana ‘Burkii’ in the BioStream. During damp springs, cedar quince rust (Gymnosporangium clavipes) produces cushion-shaped, orange, gelatinous blisters through the bark where the branches are swollen on cedars and junipers.

During damp springs, cedar quince rust (Gymnosporangium clavipes) produces cushion-shaped, orange, gelatinous blisters through the bark where the branches are swollen on cedars and junipers. photo credit: R. Robert

During damp springs, cedar quince rust (Gymnosporangium clavipes) produces cushion-shaped, orange, gelatinous blisters through the bark where the branches are swollen on cedars and junipers. photo credit: R. Robert

This fungus has a two-host lifecycle.  A few hours of wet, cool (74 to 78 degrees F) spring weather are sufficient for telial swelling on the …

Continue reading »