Effective Fungicide Use

If a student new to turfgrass management asked any lawn care operator for an explanation of the different types of herbicides, how they worked, what they worked on and the keys to a successful application, he or she would likely learn more than they could imagine. Another lawn care operator could probably give a description of insecticides that was almost as thorough and complete as the discussion on herbicides, although insecticides can be a bit more technically challenging.

But if that student went looking for some information on fungicides, there’s a greater chance that he or she would have to ask a few lawn care operators about these disease-control products before finding a knowledgeable source.

The fact is that disease incidence on turf presents fewer challenges to lawn care operators as a whole than weeds or insects do. This means that finding a fungicide expert may take a little longer than finding an herbicide or insecticide expert.

“Weed control is probably the easiest service for a lawn care operator to sell because homeowners know what a dandelion looks like, and they know they don’t want that in their yard,” related Gray Wirth, market manager for turf and ornamentals, Rohm & Haas, Philadelphia, Pa. “Insect control is probably the next easiest service to sell because once someone has grubs in their yard, they’ll never forget that.

“But disease control can be more difficult to sell because homeowners don’t know what turf diseases look like, and they will often have a disease in their yard and just think the problem is drought stress or heat stress,” Wirth continued. “That is good for lawn care operators because it means disease control represents a great add-on service to sell because the herbicides and insecticides are probably already going down on their customers’ properties, but not many of them are getting fungicides as well.”

DISEASE DEMONS. Turf diseases can be a real concern for many lawn care operators, especially those operating in areas with disease-friendly climates.

“Two factors work together to create a suitable disease environment,” noted Mike Agnew, research and development manager for turf fungicides for Novartis Turf & Ornamental Products, Greensboro, N.C. “There needs to be proper environmental conditions (warm temperature, high humidity, too much water or too much fertilizer) and a suitable host.”

“Shaded environments on residential properties are key disease areas because of the high humidity and low wind movement in those areas,” added Dr. Joe DiPaola, market manager for turf and ornamental products for Novartis. “And the low light present in the shade results in weaker turf that is more conducive to disease development.”

“Turf diseases are more difficult for us to control in this area because we’re in an area that is too hot for fescue turf and too cool for bermudagrass or St. Augustinegrass,” related Joel Adams, owner, Adams Gardening Services, Rocky Mount, N.C. “And to get the fescue to grow well in this area we have to be a little bit on the high end in terms of watering and applying nitrogen, which is basically asking for disease trouble.”

Understanding the likelihood of disease development due to climatic causes on properties you maintain is only part of the battle. Veteran lawn care operators are quick to point out that an area attacked by disease once is more likely to be attacked by a disease again in the future.

“We really target the areas where we’ve had disease problems in the past for preventive applications,” noted Adams. “And we know that if we make an application with a systemic product before the first 90-degree day we should receive pretty effective control. If we miss that mark, however, we’re going to have problems all year long.”

Adams also noted that the costs associated with fungicides and concern about making unnecessary applications limits the number of applications he’ll make on properties that haven’t had disease problems in the past. “Areas that haven’t been problems for us in the past get watched pretty closely, and we’ll spray for disease control as soon as we see the first signs of development,” he said.

A challenge for many lawn care operators, however, is deciding between a preventive or a curative strategy for disease control.

“You are probably going to spend less money and use less product treating an area in a preventive fashion than you would if you adopted a curative approach because diseases can be difficult to eliminate once they get established,” observed Agnew. “And curative treatments are tough to make by spot treating because once a fungus gets established in a lawn it is likely to spread. Just because one area of turf isn’t showing signs of the disease yet doesn’t mean the fungus isn’t getting established in that area.”

JOINING THE CULTURE CLUB. Some lawn care veterans said that fungicides can be used as a last resort in some disease-afflicted areas.

“We’ll encounter some red thread and rust every year, and we’ll get powdery mildew on our ornamentals,” noted John Knoerns-child, president, Admirable Landscapes, Portland, Ore. “But we can usually control these problems if we catch them soon enough by applying some extra fertilizer to encourage more turf growth and healthier turf.”

Knoernschild’s concern with diseases on turf or ornamentals is making sure he doesn’t help spread the disease to other properties. “Obviously, you want to prune any infected areas of a tree or shrub so long as doing so won’t harm the plant, but then you have to be careful not to let infected leaves lay on the lawn where the disease can get into the turf,” he explained. “We make sure we sterilize our pruning shears or mower blades with alcohol after we’re done with any property that has disease problems so we don’t carry the fungus to the next property.”

Lawn care operators should also work with homeowners to help avoid encouraging disease development. “You want to avoid doing anything that would extend the leaf wetness period, which is the time from when the dew first starts forming on the turf at night until all of the moisture has evaporated the next morning,” explained Wirth. “A big problem here is irrigating the lawn in the morning when the turf is trying to dry out.”

PRODUCT SELECTION. While much of the attention surrounding the re-registration of pesticides called for by the Food Quality Protection Act (FQPA) has focused on the organophosphate insecticides, fungicides have also been impacted.

“Curalan, Daconil and Chipco 26GT have all had their labels impacted by FQPA, and this means there are fewer options for lawn care professionals to use,” noted DiPaola.

Wirth said the spectrum of control offered by a fungicide and its residual are key areas for fungicide buyers to focus on.

“Not all lawn technicians are well trained on disease identification, which can be challenging because a lot of diseases have similar symptoms but different causes,” he noted. “So having a product with a broad spectrum of control is important.

“A product’s residual is also important unless you are going to be on the property every two weeks or so,” he continued.

Wirth said one trend he has seen of late is for more turf managers to tank mix a systemic fungicide with a contact fungicide (see sidebar, page 78) in order to reap the benefits of both product types.

“The contact product delivers the quick knockdown and broad spectrum of control, and the systemic product extends the length of control delivered by the application,” Wirth explained.

And since some golf course superintendents are reportedly encountering instances of fungicide resistance on the turf they manage, Wirth encourages lawn care operators to consider developing a fungicide program that rotates products.

“Since the industry has lost the use of some products, there is a danger of making too many applications of fungicides with the same mode of action,” he explained. “We’re seeing the development of fungicide resistance as a result of consistent mode of action use now, and doing this is asking for trouble in the future.

“Lawn care operators need to understand the chemistry involved in the products they use and how those chemistries work, but they also need to understand the different modes of action,” Wirth continued. “Products can have different chemistries but the same mode of action, and that can create problems.”

The author is Editor of Lawn & Landscape magazine.