Monthly Archives: November 2013

The Tale of Two Beetles: How they kill trees

By Joe Boggs, Amy Stone, and Dan Herms

Both beetles are tree-killers and exhibit no real preferences for stressed versus healthy trees. However, EAB only infests and kills trees in one genus (Fraxinus), while ALB infests and kills trees in 13 genera. Trees considered good hosts of ALB include:
Acer (all maple species);
Aesculus (horsechestnuts and buckeyes);
Ulmus (elms); and
Salix (willows).

Trees considered ‘other’ hosts include:
Betula (birches);
Platanus (sycamore/plane trees);
Populus (poplars);
Albizia (mimosa);
Cercidiphyllum (katsura);
Fraxinus (ashes);
Koelreuteria (golden rain tree);
Sorbus (mountain ash); and
Celtis (hackberry).

While the good hosts in this list of genera are generally considered the trees most commonly attacked by ALB, all these trees can be attacked and killed by ALB.

Read the full article: The Tale of Two Beetles

An Ounce of Prevention: A new option

Equipment operators should become familiar with different fuel types and their impact on engine performance, and ensure any gasoline being pumped is approved for use in their specific engine model. Photo courtesy Kohler Engines

By Scott Mack

One new option for turf professionals looking to avoid carburetor maintenance issues is to select equipment with electronic fuel-injected (EFI) engines. Since they do not have a carburetor, they eliminate the related hassles. Additionally, fuel within an EFI engine is sealed off from the air so it will not evaporate while in storage.

Another important factor behind the rapid acceptance of EFI engines has been the enhanced fuel efficiency they provide. For example, a line of proprietary equipment using a closed-loop system has been demonstrated to help save end-users up to 25 per cent in fuel when compared to one of the company’s carbureted engines under comparable load conditions. This means turf professionals can save up to US$600 per engine in annual operating costs.

Read the full article: An Ounce of Prevention

The Tale of Two Beetles: What to look for

EAB creates a characteristic ‘D-shaped’ emergence hole. Photos courtesy Joe Boggs

ALB are bigger beetles, measuring around 25 to 40 mm (1 to 1.6 in.) in length.

By Joe Boggs, Amy Stone, and Dan Herms

EAB is a much smaller beetle, measuring around 10 to 13 mm (0.4 to 0.5 in.) in length. Adults have a flat back and round ‘belly’ when viewed head-on, which is the orientation of the beetle as it emerges from trees. Thus, EAB creates a characteristic ‘D-shaped’ emergence hole. Owing to the beetle’s small size, the holes are only around 4 to 5 mm (0.2 in.) across the flat side of the ‘D.’ The relatively small size of the exit holes makes finding them difficult until trees are heavily infested. Adding to the challenge is the tendency for the beetles to first infest the uppermost and outermost branches and then gradually work their way inward and downward with each successive generation. Consequently, exit holes are usually found at eye-level only when infested trees have been almost completely used by the beetles.

ALB is a large beetle, measuring around 25 to 40 mm (1 to 1.6 in.) in length. They have characteristically long antennae, with each one measuring as long as 40 to 50 mm (2 in.). The beetles produce large, round exit holes that can be almost 10 mm (0.4 in.) in diameter. Since the larvae feed deep within the xylem, the exit holes extend deep into the tree. Inserting a pencil into an exit hole is a good way to determine whether the hole was produced by a xylem-emerging borer. This is the so-called ‘pencil test.’ ALB does not appear to follow the same distribution pattern within a tree as EAB and exit holes are almost as likely to be found at eye-level as they are high in the tree’s canopy.

Read the full article: The Tale of Two Beetles

The Evolution of Turf Diseases: Fundamentals for a moving target

Although dollar spot has been around since the 1920s, it remains one of the most expensive diseases to manage. Photo courtesy John Kaminski

By John Kaminski, PhD

The bottom line is disease management is not a stationary target. Turfgrass managers must keep current with the latest information on emerging diseases and the latest products available. They must also continue to review fundamental concepts such as disease lifecycles as well as the biology of the turfgrass pathogens. Only when a manager can grasp all the concepts surrounding the pests and current chemical and cultural management options can they make the best decisions when it comes to keeping their turf healthy.

If nothing else, the evolution of turfgrass diseases will result in two things: it will ensure only those that keep up with all of the changing information are able to successfully control their disease problems, and it will ensure turf pathologists around the world are forever employed.

Read the full article: The Evolution of Turf Diseases

Managing Difficult Plant Diseases: Weather is unpredictable

Bacterial fireblight only occurs on certain plants in the rose family, such as Callery pear (pictured), crabapple, mountainash, pyracantha, and cotoneaster. Photo courtesy James Chatfield

By James Chatfield, Joseph Boggs, and Erik Draper

The environmental component of the disease triangle is crucial for plant diseases. Plant pathologists talk about infection periods for specific plant diseases and whether these periods occur depend on such things as the number of hours of leaf wetness and relative humidity. Of course, this in turn is influenced by temperature. All this plays into the overall weather, which can be difficult to predict over the short term, to say nothing of an entire growing season.

Temperature and moisture, for example, play a big role in development of fireblight disease. Bad years for fireblight on callery pear or crabapple usually relate to how warm and wet it is during bloom. The years where there are massive blossom infections—the greatest occurrence is during wet weather during extended periods over 16.7 C (62 F)—are those where fireblight is worse. So, it depends on whether these conditions occurred during the bloom of a particular callery pear or crabapple in a particular part of the province or region.

Read the full article: Managing Difficult Plant Diseases