Spring is a busy time in nurseries and greenhouses because of the wide variety of plants in production. The diversity of plants also presents the challenge of preventing the many insects and diseases that could threaten healthy, salable crops.

As you near the end of bedding plant production, it’s important to maintain the same diligent protection to prepare crops to reach consumers. In the last weeks of production, your bedding plants are still at risk of diseases including Botrytis and powdery mildew, as well as insects such as thrips.

What to watch for

Botrytis, or gray mold, thrives in cool, humid environments. It is especially threatening during spring production and when plants are being prepared for shipping. Initial signs of Botrytis include small, water-soaked spots on foliage and flowers. When scouting for Botrytis, look for symptoms such as small, light brown spots or tiny flecks on flowers and V-shaped, tan-brown lesions on foliage. Gray, fuzzy sporulation on infected tissue is a sign of an active infection.

Powdery mildew first appears as white, talcum-like spots called “colonies” on leaves, stems and flowers. If uncontrolled, the colonies grow to cover the plant’s surface and can cause leaves to turn yellow, brown and then drop. Sometimes, such as in calibrachoa, sporulation is sparse, and infections occur in the lower canopy causing leaf collapse.

Thrips are tiny, elongated insects that feed by scraping and piercing plant tissue and sucking out the sap and cellular contents from leaf tissue, flower buds and/or unexpanded shoot tips. As a result, leaf stippling (silvery streaking), scarring and distortion can occur. In addition to physical injury, several types of thrips can transmit tospoviruses, such as impatiens necrotic spot virus and tomato-spotted wilt virus; which can quickly spread throughout the greenhouse.

Protection with product rotations

As you near the end of production, follow recommended production rotations in an agronomic program, such as this one from Syngenta, until your crops leave your operation. For example, the Syngenta spring bedding plants agronomic program includes both Postiva™ fungicide and Mainspring^® GNL insecticide. Postiva features a combination unique to the ornamental market in FRAC Groups 7 and 3, while Mainspring GNL is a neonicotinoid alternative with the novel active ingredient cyantraniliprole, which belongs to IRAC Group 28, a recently added chemistry class. Drench with Mainspring GNL once plants are rooted in for long lasting protection against thrips.

An agronomic program that rotates powerful products like these helps prevent resistance and preserve valuable chemistries, providing a framework for protecting your crops from the most common problems.

Ensure crops remain healthy through storage and shipping by completing product applications as directed in an agronomic program.

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