Attacking the pathogens

Photo courtesy of OHP

Most greenhouse-grown crops are susceptible to plant diseases, but cultural practices and fungicides can curb those diseases. Dr. Carlos Bográn, technical manager at OHP, discusses some remedies.

Greenhouse Management: How do disease issues crop up in the greenhouse?

Dr. Carlos Bográn: Disease epidemics occur when susceptible crops are grown under conducive conditions in the presence of pathogens and other stress factors that compromise the health of the plants. Disease-causing microorganisms can survive inside or outside of the greenhouse, or can be brought in with propagation material. And when temperature and relative humidity conditions are favorable for infection, diseases can spread quickly. Inappropriate use of crop inputs like water, fertilizer and plant protection chemicals can also lead to crop damage and loss. Although not all plants get all diseases, most greenhouse-grown plants are susceptible to at least one important plant disease.

GM: Which disease issues do you find are most prevalent in the greenhouse?

CB: Both foliar and root diseases are common in the greenhouse and depending on the type of plant, the growing season and the production system, foliar diseases might be more or less prevalent than root diseases. Diseases caused by fungi and bacteria tend to be the most prevalent in greenhouses. 

GM: What measures can growers take to prevent diseases?

CB: Good cultural practices including sanitation are key in preventing plant diseases. Managing temperature and relative humidity inside the greenhouse to favor plant growth and avoid disease-conducive conditions are essential in limiting plant disease epidemics. Accurate and timely use of crop protection products can help further reduce the risk of plant diseases, as well as control of plant disease vectors such as thrips and whiteflies.

GM: What are some of OHP’s newest developments in fungicides?

CB: OHP just launched Astun*, an ornamental fungicide with Isofetamid, a 4th generation SDHI tool for control of Botrytis and related diseases. As a stand-alone SDHI (MOA Group 7) fungicide, it is a great tool for managing gray mold, including fungicide-resistant strains of Botrytis, while providing flexibility in tank mixing based on the target crop and disease complex.

GM: Can you explain the mode of action of Astun?

CB: Astun works by disrupting the cellular-energy making process of the target pathogens, rendering them unfit to cause infection. Astun is systemic, works extremely well in preventive applications, but also has great activity after the initial detection of disease symptoms as an early curative.

GM: When setting up a fungicide rotation should I go by chemical class or mode of action?

CB: It is always better to rotate on mode of action. There are a few fungicides that have different chemical classes but the same MOA, so those would be separated in a rotational program. Refer to the OHP Chemical Class Chart for help. www.ohp.com/Literature/pdf/CCC_XIII.pdf— Interviewed by Patrick Williams

*Astun is manufactured by ISK