Features Fungicides Seed & Chemical
Improving plant health with fungicides

It is an easy sell to explain how fungicides control yield robbing diseases. However, there are other benefits to using these products wisely. In some cases plant health is improved, not only because disease is controlled, but also because the healthy plant is more capable of absorbing nutrients and moisture. It requires careful management to get these benefits because growers must always be wary of diseases developing resistance to the products.

Flexible products give growers options when it comes to managing diseases and improving plant health. Eugenia Banks, potato specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs, says Quadris, a strobilurin fungicide, can be applied at planting in-furrow to control rhizoctonia, which promotes plant health. But when used as a foliar spray, Quadris will also control early blight. She says Quadris, made by Syngenta, is a good example of how one fungicide can have two functions. “When used as an in-furrow treatment, Quadris will protect the roots and developing tubers,” Banks explains. “Using it in a soil application will not accelerate development of resistance in the early blight fungus population.”

It is best to use disease management products in a rotation program.

Harold Wright of Syngenta says Quadris will preserve the green growth of the plant when it is used as a foliar protection against early or late blight. But since it also controls rhizoctonia and Helminthosporin in-furrow, there is a reduction of diseases that can reduce plant health. He adds that silver scurf was added to the label in 2007, which means growers will have control of an unsightly fungus as well. “Plant health can be optimized if you control diseases that affect the green leaf area of the plant,” Wright says. “We have also seen evidence that Quadris helps with water use efficiency in the plant and carbon dioxide assimilation. Growers will definitely see yield boosts if plant health is maintained.”

Wright cautions growers against using only one tool to combat disease. Of course he wants to see his products used, but he wants them to be part of an overall use strategy that has resistance management as a key element. “There are many tools available but growers need to use the best tools in a rotation program to maximize the life of the chemistry,” he cautions. “Quadris is effective, but we want it to be used wisely.” This means ensuring that foliar treatments are applied preventively before disease development.

The attractiveness of Quadris is that it has multiple use patterns that allow growers to target several diseases without increasing the risk of resistance development. According to Wright, the Global Fungicide Resistance Action Committee has ruled that using Quadris in-furrow does not compromise its use as a foliar. This is because the two uses target different disease problems at different times.

“Many growers claim that Quadris makes the potato skin more attractive as well,” adds Banks.

Wright says that reducing disease pressure will produce attractive results because the plant is healthy and black scurf and silver scurf, which are often to blame for blemishes on potatoes, will not be present to create the problem.”

In store bins where smooth skinned, blemish-free potatoes are the first to be chosen and in processing where deep blemishes lead to losses in production, the attention to plant health is appreciated and, in the case of processing, rewarded. With flexible products, control of disease is effective and there is reduced risk that resistance will develop while growers will have healthier plants that will produce better. -end-