Boxwoods losing leaves should not be ignored!! Check them carefully for tell-tale symptoms of boxwood blight, a serious fungal disease that causes rapid defoliation and dieback (Fig. 1). The fungus that causes boxwood blight can infect all above ground portions of the shrub. The first symptoms of the disease are dark leaf spots (Fig. 2 ) that progress to twig blight and rapid defoliation (Fig. 3) and eventual death of the plant if it goes undetected (Fig 4). The narrow black streaks (cankers) that develop on green stems (Fig. 5), are a unique symptom that differentiates boxwood blight from other boxwood diseases. During periods of high humidity, white, fuzzy masses that consist of numerous clumps of spores will emerge from these black stem cankers (Fig. 6) as well as on the underside of leaf spots. The spores can be observed on infected stems and leaves with a hand lens. These[Read More…]
Archives for August 2018
Tree inspections are important for every tree owner to protect people and property and reduce liability.
An abiotic stress in plants is a stress due to a non-living factor, such as temperature, moisture, herbicides, etc. Biotic stress includes a living organism, such as a fungi, insect, etc. This series will explore some of the most common types of abiotic stress you may find in landscapes and nurseries. What is wrong with this maple? How would you correct the problem? If you guessed manganese deficiency, you would be correct. In areas with high pH, such as many locations in the Midwest, manganese (Mn) deficiency in maple is very common. When the pH of the soil is above 7, manganese is not readily available to the plant, even if there are sufficient amounts of manganese in the soil. As the pH of the soil increases, manganese is less and less available. We tend to begin seeing manganese deficiency when the pH is above 6.3 (Fig. 1). [Read More…]
Diseases that affect the twigs, branches, and the main trunk of a tree are referred to as cankers or blights. Cankers appear as a general sunken area of darkened tissue on the twigs or branches, often surrounding a branch stub (Fig. 1). Canker diseases can be a serious problem in the landscape when they are not properly managed, and even when they are. All woody plants can be infected by canker pathogens. Many canker pathogens produce fruiting bodies, which contain sacs of spores (asci or conidia) that forcibly release the spores when the conditions are right. These pustules are easy to find on the surface of the canker (Figure 2). As the canker grows, the twig or branch may become girdled, causing the wilting and death of the leaves past the point of infection on the tree. On stone fruit, this can cause gummosis, too (Fig. 3). What causes[Read More…]
Q. We have a large sycamore tree in our yard. Every summer it sheds its bark over a few weeks’ time. I think as it grows it is growing new bark and losing the old bark. Am I correct? – J.C., Walton, Ind. A. You’re on the right track. Peeling bark is normal, and is a key ornamental characteristic for a sycamore, also known as American planetree. The bark starts out a bit gray-brown and as the bark matures, the outer layer peels off in large sheets to reveal a lighter-colored, creamy, off-white inner layer. The result appears a bit like a camouflage pattern. No need to worry – the tree is not harmed by the peeling bark.
The Purdue University College of Agriculture hosts a career fair every fall and spring semester. Over 150 companies attend, providing recruiters with the opportunity to educate students about their organizations, advertise positions and/or interview students for permanent or internship positions. During the fall, a Resume Blitz is held the day before the fair. The evening prior to the Fall Career Fair, we host an Employer Panel Discussion. This is an open dialogue with 100 students, lasting 60 minutes, followed by a networking session. If your company is interested in participating in either pre-fair event, please indicated your preference on the registration form for the fall fair only. The College of Agriculture will host the Fall 2018 Career Fair on Tuesday, October 2, 2018, 9:30 am to 3:30 pm in West Lafayette. For registering your company with the fair, or for more information, please visit the website at: https://ag.purdue.edu/oap/career/Pages/Employer_Career_Fair_Main.aspx Registration ends at[Read More…]
Control spider mites by mechanical control and improving conditions for predators and fungi. If needed, follow up with pesticides to rescue ailing plants.