Monthly Archives: November 2013

The Evolution of Turf Diseases: Developing super-pathogens

Breeding programs continue to help improve the tolerance of turf to various diseases. Photo courtesy John Kaminski

By John Kaminski, PhD

Another major factor in the evolution of disease management is the ability (or lack thereof) to manage pathogen resistance to fungicides. Rotation of chemical classes, proper use rates, and tank-mixing are a few ways to help delay or prevent the onset of resistance. Other factors, however, play an important role in the efficacy of the fungicides.

One of those factors is the timing of the applications. Many law-makers and those who do not really understand the biology of pests or the management of turf often suggest that waiting until symptoms appear is the most environmentally sound way to use pesticides. This author gets into these discussions routinely and does his best (although it sometimes may fall on deaf ears) to explain why this may not always be the case.

As an example, dollar spot is a prominent disease on golf courses and can occur over extended periods. Targeting this disease preventively is an excellent way to keep inoculum levels down and therefore prevent damage from occurring. Curative control (i.e. after symptoms have developed) is often difficult and comes at the expense of higher pesticide use rates, shorter application intervals, and increased potential for resistance development. In these cases, letting the disease develop before implementing a chemical control can actually result in an increase in pesticide use and loss of currently effective products through resistance.

While this concept can sometimes be difficult for those who do not understand disease lifecycles and epidemiology, it is the same concept that allows turf professionals to choose which diseases should be treated preventively versus curatively. Diseases such as take-all patch, dollar spot, summer patch and the snow moulds are more effectively managed when pesticides are applied preventively. On the other hand, diseases such as brown patch and even rust to some extent can quickly be squelched with a curative application.

Read the full article: The Evolution of Turf Diseases

The Tale of Two Beetles: Where they came from

In 2003, Asian longhorned beetle (ALB)—Anoplophora glabripennis—was found in Toronto. Photos courtesy Joe Boggs

By Joe Boggs, Amy Stone, and Dan Herms

Both insects were accidently introduced into North America; however, EAB appears to have had a single point of introduction in a suburb of Detroit, Mich., whereas ALB has been introduced from China to multiple sites in North America. So far, no ALB infestations have been found to be linked to other infestations in North America; all the beetles that began new infestations arrived directly from China. However, there has been a repeating pattern for each new infestation where a single point of introduction from China was then followed by multiple infestations within the region, which was the result of the movement of infested wood or other material before the discovery of ALB in the area.

Although ALB’s 1996 discovery came six years before EAB, the latter has become much more widely distributed in North America (even though ALB was introduced to multiple locations). Explanations for this disparity in the current distribution of the two beetles include differences in signs and symptoms, and thus the ability to detect the beetles, as well as their behaviour.

Read the full article: The Tale of Two Beetles

Emerald ash borer (EAB)—Agrilus planipennis—was discovered in Toronto in 2007.

Managing Difficult Plant Diseases: Disease control is preventative, not reactive

Apple scab disease on crabapple occurs only on certain crabapple types. Though it does not kill the plant, it may make them unsightly with considerable leaf drop. Photo courtesy James Chatfield

By James Chatfield, Joseph Boggs, and Erik Draper

Since green industry professionals cannot see inoculation and infections occur, they must act proactively with regard to plant diseases. In many cases, this means they need to use fungicide applications to prevent the germinated fungal spore from getting into plant tissue in the first place (though there are systemic fungicides that sometimes help).

A better, more sustainable approach is to employ their knowledge of genetic disease resistance, plant health, and plant stress management to optimal effect. Green industry professionals need to recognize Sargent and Adirondack crabapple have excellent resistance to apple scab, compared to thunderchild and hopa. If they know there is a site with the Verticillium fungus well-established in the soil, which they can know from previous Verticillium wilt diagnoses, then they should not plant highly-susceptible species such as Japanese maples (Acer palmatum).

Selecting the right plant for the right site is the greatest preventive maintenance practice tree professionals can use, not only for infectious disease management, but also for overall plant health. Eastern redbuds planted in open sun on unirrigated sites are more likely to become moisture-stressed and are more likely to have Verticillium wilt problems as well as Botryosphaeria canker disease—the two most common infectious disease problems of Eastern redbuds that cause stem dieback and eventual plant death. Preventing these diseases from the very beginning can occur by not planting redbuds in those sites.

Read the full article: Managing Difficult Plant Diseases

The Evolution of Turf Diseases: Changing management strategies

Understanding basic information about fungicides is critical in resistance management. Photo courtesy John Kaminski

By John Kaminski, PhD

Between old diseases emerging as more prominent problems, uncommon pathogens becoming more common, and entirely new pathogens appearing, the turfgrass pathology community is constantly evolving.

How does this impact turf professionals and the management of their issues? If they are one of the fortunate superintendents in the areas where pesticide restrictions are limiting the ability to manage the diseases, they are lucky. If they do not have the ability to do anything about it, then there is not much that can be done. The reality of disease management under the high pressure observed on golf courses is often too much to handle soley through changes in cultural management programs and, unfortunately, biological controls have been met with limited success in high maintenance turf.

If there is still a limited arsenal of control options available, then he or she may be one of the lucky ones. However, this does not mean reliance on chemical control should be the first option. Choosing sound cultural practices for the species being managed is the first place to make adjustments. Growing the healthiest plant possible is going to make the fungicides more effective.

Read the full article: The Evolution of Turf Diseases

An Ounce of Prevention: Seasonal considerations

Outdoor power equipment should get special attention at the end of each season, including changing the oil and removing dirt and debris. Photo courtesy Kohler Engines

By Scott Mack

All outdoor power equipment should get some special attention at the end of each season. An oil change must be performed to ensure clean oil is coating the engine while it is being stored. Many turf professionals do not realize that part of the byproduct of engine combustion includes acid and water. Adding 29.6 mL (1 oz) of fresh oil to each cylinder and rotating the engine are recommended to help protect the cast iron lining against water condensation and its corrosive properties.

Any loose clippings and dirt should also be removed from equipment at the end of each season. Most dirt can easily be removed with soap and water, but a wire brush may be helpful; a putty knife can even be used to carefully scrape away ground-in debris from the underside of equipment. It is not uncommon for rodents to nest in dirty machines while in storage, so turf professionals should not make it easy for them.

Read the full article: An Ounce of Prevention