During the fall and winter, cooler temperatures and overcast weather create prime conditions for pathogens such as Pythium spp. to establish, which can cause root and stem rots to invade wounds and tender plant tissue. This jeopardizes healthy roots, posing a threat to unrooted cuttings and young seedlings in propagation, as well as to established plants.

Spotting Pythium

One of the most effective ways to prevent damage caused by this pathogen is to be aware of the warning signs, which include:

• Young seedlings that collapse shortly after germination or are severely stunted and appear nutrient deficient
• Transplants and unrooted cuttings developing a lower stem rot
• Infections on established plants causing lower leaves to turn yellow and defoliate
• Plants wilting during the heat of the day, recovering at night
• Roots that are soft and brown with a water-soaked appearance
  • The outer portion of the root is easily removed, leaving behind the stringy vascular core of the root

Methods for Prevention

Implementing cultural practices coupled with an effective fungicide rotation program is the key to protecting plants against Pythium spp.

Cultural tips to prevent the development of Pythium infection include:

• Cleaning the benches and growing areas of debris and sanitizing between crops
• Providing appropriate plant spacing to allow for good air movement
• Elevating pots in low areas where water may pool
• Keeping the humidity low by heating or venting
• Immediately removing any diseased plants from the area to limit spread

Additionally, fungicide programs must include a product rotation to deliver broad, reliable disease control.

Effective solutions include Subdue Maxx^® and Mural^® fungicides from Syngenta.

Subdue Maxx is a systemic fungicide with protective and curative activity against oomycete pathogens such as Pythium and Phytophthora spp. Interfering with key development processes such as mycelial growth and spore formation, treatment halts disease progression while protecting new roots. 

Subdue Maxx can be applied alone or in combination with Mural for broader activity against common root and stem pathogens including Rhizoctonia, while also providing plant health benefits and additional Pythium protection.

Learn more about agronomic solutions at GreenCastOnline.com/Ornamentals.

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