"Addressing fusarium fruit rot in peppers”"

Internal rot is a big risk in pepper cultivation. Jantineke Hofland, Plant disease specialist at Wageningen UR Greenhouse Horticulture in Bleiswijk, has conducted extensive research on the Fusarium fungus responsible. She also looked at the effect of the biological agent Serenade.

“We've learned a lot about fusarium fruit rot in a short time,'' says Hofland. The plant expert has been closely involved in a large research project on the disease in the last few years. The project was started after pepper growers suffered large-scale damage in 2012. Hofland: “Growers were used to the disease appearing now and then. But this time something just had to be done. In a unique collaboration with other research institutions we combined the available knowledge and did additional research.”

Internal fruit rot is a complex problem that starts with the contamination of the flower. The climate in the greenhouse clearly plays a role here. In the year 2012 it was difficult to control the humidity in the greenhouse, so the disease could easily infect the flowers. Hofland: “Within five days a spore can grow into the pistil or stamen and affect the ovary. Once there, it is too late to intervene. So you have to take preventive action.'' In addition to the greenhouse climate, the disease burden plays a role. “Spores are widely present in greenhouses and infection can occur even with a low spore burden. Still, it makes sense to minimize the spore burden. It reduces the risk of infection,'' the researcher says.

In order to test different measures in a short time, Hofland and her colleagues developed the so-called flower test. The pepper flowers are treated with a product and then artificially infected with Fusarium lactis. The ovary is then placed on a growth medium to grow further. “That way we did not have to bring diseases into the greenhouse."

One of the agents used in the tests was plant protection product Serenade. “We saw pretty quickly that the agent is very effective. It reduced contamination by 50 percent. With antagonists the effect may be less in the case of a high spore burden. But we did not find this with Serenade.

"When applying the product, it is important to start early. Once the fusarium fungus has formed, mycelium control is much harder because Serenade mainly works preventively,'' Hofland explains.

According to Hofland, Serenade fits well into the comprehensive approach she says is necessary to keep the disease under control. “Internal fruit rot is a complex problem that you can only control with a range of measures. That starts with prevention. Besides working hygienically, you should prevent the buildup of disease pressure as much as possible." That can be done by protecting the crop with Serenade before every setting. If applied in time, Hofland expects a good preventive effect, also against other fungi such as Botrytis and powdery mildew.

Another form of prevention is to work on the greenhouse climate. In research to be launched this year, the water balance of the crop will be looked at, among other things. There are possibilities to make the crop more resistant on the breeding end as well. Hofland is keeping all options open and wants to gain experience in the use of green measures in collaboration with growers. “I notice that green products still have to earn their place. But I think we just need to try them out. A systematic approach will get you further than a one hundred percent chemical one.''