Apple Scab, Bagworm and Black Knot

Trees in Spring

The Bark

As a reminder, we are still treating Apple Scab, and treatments will continue throughout April. If you have not started treating yet this year, we will put you on the schedule for next spring! If left untreated, major defoliation is possible in summer leading to more stress for your trees. This is an annual treatment and is best paired with accompanying health treatment. This combination will stop the disease for the growing season while also helping to increase the overall health of the tree.

Bag Worm

he bagworm (Thyridopteryx ephemeraeformis) is actually a caterpillar! This pest is native to the United States and is commonly found in Eastern regions. It can affect over 50 families of trees and shrubs, both evergreen and deciduous. The larvae begin to appear from last year’s bag, pictured on the right, in mid-May to mid-June. During the larval stage, the insect feeds on the leaves and needles of trees and shrubs. The chewing mouthparts of the larvae defoliate the stems and branches and can cause serious dieback or death if left untreated for an extended period of time. The female caterpillars are not able to fly and most will remain on the same tree. You often see the host become more infested year after year because of this. The treatment window for the bagworm is important as they are more vulnerable to treatments when feeding. As an extra preventative measure, in the fall it is recommended to remove the bags from the tree and dispose of them as the bags contain the next year’s larvae.

Black Knot Fungus

The disease, Dibotryon morbosom, commonly known as Black knot fungus, gets its name from the black and knotty outgrowth it produces. Infection from this fungus occurs in the spring when spores are transmitted from wind or splashed in the rain onto new growth. The fungus disrupts the normal flow of water and nutrients in plum and cherry trees when growing on the branches and stems, causing dieback within the canopy. The first stage of infection has no visible symptoms, with stages two and three pictured below. The treatment window generally begins in early to late April as new growth extends from the tree. The treatment should be accompanied by pruning and health treatments. We advise the removal of trees that have a canopy with over 30% infection. Black knot is an extremely difficult fungus to detect during the first year of infection and progressively more difficult to treat throughout the advancement in the tree.

Essential Business Order

A message to our amazing friends, customers and clients. With the uncertainty of how things are going in the world and even in our beautiful city, we hope that all of you are doing well and staying healthy. We appreciate all that you have done for us and we want to let you know that we are here for you. Joseph Tree is fully operational and will continue on through this troubling time to give our customers and clients the best and most safe work as we are able. We feel as if we are able to maintain the social distancing along with upholding our strong values in personal protective equipment for our employees. Our production, plant health care, and sales teams will remain in the field and caring for your urban forest. Thank you and take care.