Several caterpillar pests feed on trees and shrubs in July. Although most trees can tolerate some defoliation, the injury can be unsightly for much of the summer. Damage to plants can be reduced by timely applications of insecticides. Proper choice of insecticides can reduce impacts on pollinators and natural enemies of spider mites that do well during the heat of the summer. Foliar applications of insecticides can be a challenge for homeowners. Although some products can be applied to the soil, label precautions must be followed to ensure that the insecticide reaches the canopy and does not burn leaves. Early detection of caterpillar activity is critical to successful control of these pests because smaller caterpillars are killed more easily by insecticides. While some caterpillars are easy to spot on small trees and shrubs, most are invisible to the naked eye from the ground. It is much easier to spot fecal[Read More…]
Late frosts and wet weather were especially hard on oaks this spring. Surviving leaves on many oaks did not grow normally. Sustained warm weather in the summer will allow oaks to grow past their injury and thrive. Oak tatters is a common response to cold snaps in the late spring. Leaf growth is distorted. Affected portions of the leaf do not expand normally and appeared to have been chewed and left in tatters. Nothing can be done to remedy the situation other than to wait until new growth occurs. When the weather warms, healthy oaks will grow new leaves to replaces those that have been distorted by tatters. Most trees will survive bouts of tatters. Adult flies make holes in leaves that when they lay eggs into expanding leaves. Eggs hatch into a maggot that makes a small blotch mine in the leaf. When the leaf tissue drops out,[Read More…]
Trees and shrubs can lose their leaves for many reasons. The maple tree in the cover photo is planted in a parking lot, and mulched incorrectly. The parking lot location gives the tree much less access to rainwater than a tree planted in a park-like pavement free location. Deep mulch piled like a volcano aggravates water problems because much of the rain will roll off rather than penetrate the soil at the tree base. Also, the base of the trunk is buried as if the tree has been planted too deeply. This can cause the tree to develop a second set of roots and wreak all sorts of havoc from girdling the trunk to making it even more difficult for a tree to get water from the soil. Scale insects can only make this tree’s problems worse. Oystershell scales are among the more common armored scales that are attack[Read More…]
Jumping worms (a.k.a. snake worms, crazy worms, Amynthas spp.) While you’re gardening in the coming weeks keep your eyes peeled for jumping, wriggling worms. Asian jumping worms are spreading in the Midwest and they can do serious damage to your yard. Where are they from? No one is sure exactly how jumping worms were introduced into North America but it’s likely that they were brought over from Asia in soil used for potted plants, landscaping material, or agricultural material. What do they do? These worms are hungry and reproduce quickly! Unlike most other earthworms which prefer lower layers of soil, jumping worms prefer the top layer where organic material needed for plant growth is concentrated. They quickly eat the organic matter in the topsoil which makes it difficult for plants to grow and other soil animals to survive. In forests this change can greatly reduce the number of[Read More…]
Earthworms are not the only wigglers in the soil beneath your feet. Nematodes, microscopic roundworms, can be found in soil across the globe (even Antarctica!) and are often a barometer of soil and environmental health. However, the nematodes we encounter more frequently feed on plants and cause us, as plant stock producers and consumers, a ton of headaches. One subset of the plant parasitic nematodes that stands apart from the rest are the foliar nematodes (Aphelenchoides spp.). Unlike the vast majority of nematodes which strictly inhabit roots and soil, foliar nematodes (as their name suggests) live in and feed on leaves, stems, and buds. They enter the plant through stomates, natural openings for gas exchange in the leaf surface. As they feed, symptoms of foliar nematode injury appear as water-soaked lesions that eventually turn brown over time. With a broad host range of more than 700 different plant species, symptoms[Read More…]
Join us May 12th at 4:00 pm (EDT) at this link: https://purdueextension.zoom.us/j/92562247848 The Purdue Green Industry Team and Indiana Nursery and Landscape Association would like to invite you to a virtual event for the Green Industry and other Agri-Businesses featuring United States Senator Mike Braun. He will be providing updates for Agri-Businesses from the federal government. The state director for his office, Jason Johnson, will follow the senator by hosting a Q&A with the industry. In addition to Senator Braun and Jason Johnson, Rick Haggard will give an update from the Indiana Nursery and Landscape Association and Dr. Cliff Sadof will provide information on Asian giant hornets, spotted lantern fly, and other invasive species. U.S. Senator Mike Braun: Update for Agri-Businesses from Washington, D.C. Jason Johnson, State Director, Office of Senator Mike Braun: Q&A from the Senator’s Office Rick Haggard, Executive Director, Indiana Nursery and Landscape Association: Update for the[Read More…]
The presence of these hornets in the United States is could be bad news for honeybees and native insects alike but there’s no need to panic yet.
Labor issues and timing of tree care activities have been and will continue to be impacted by federal and state rulings as a result of CoVid-19. As a result of social distancing and confusion surrounding “essential services”, many plant health care technicians and business operations have been suspended. As the season progresses, these labor suspensions can make it difficult to apply pesticides and fertilizers when they can most benefit turf, ornamental and overstory trees. Emerald ash borer, Agrillus planinpennis, continues to be the most serious problem facing ash trees in much of North America. Timing is important to get the best results with the least amount of canopy thinning and health maintenance. Data from several university studies have shown that spring insecticide treatments are consistently more effective than the same treatments applied in fall. Research conducted in Purdue laboratories on large trees shows that this is particularly important if you[Read More…]
Tent caterpillars have started hatching. How should you handle them?
When houseplants and garden seedlings are kept too wet, roots can rot and the fungus that grows in the soil can feed fungus gnats. For houseplants, fungus gnats are usually just a nuisance. When growing seedlings or in a greenhouse adults can spread fungal diseases to flowers. Larvae can spread fungal diseases when they feed on roots. Where do fungus gnats come from? Fungus gnats can get in the home when plants are brought in from outside, or when transplanting plants with infested potting soil. How do you manage fungus gnats? Avoid over-watering your plants. Plants need less water in cloudy days in winter and spring. As such, it is easy to over-water plants if you water by the calendar. It is better to check you plants to see if they need water by touching the surface to see if it is dry. After you water, do not let plants[Read More…]