Pointers for Fall Pythium Prevention

Root and stem rots caused by pathogens such as Pythium spp. are more prevalent in the late fall and winter when days are overcast and greenhouse temperatures are cooler. These conditions cause growing media to remain wet for longer, presenting ideal opportunities for oospores of Pythium spp. to germinate and invade wounds and tender plant tissue. Don’t let Pythium sneak into your production by preparing with proper cultural practices and an effective fungicide rotation program.

Identify Infection

Young seedlings infected with Pythium will collapse shortly after germination or appear severely stunted and nutrient deficient. Transplants and unrooted cuttings may develop a lower stem rot, whereas infections on established plants cause lower leaves to turn yellow and defoliate. Infected plants will wilt during the heat of the day and recover at night. Infected roots are soft and brown with a water-soaked appearance. Also, the outer portion of the root can be easily removed, leaving behind the stringy vascular core of the root.

Pythium root rot on poinsettia, Rechcigl

Implement Key Cultural Practices

Cultural tips to prevent the development of Pythium infection include:

  • Clean all benches and growing area of debris and sanitize between crops
  • Provide appropriate plant spacing to allow for good air movement
  • Elevate pots in low areas where water may pool
  • Keep humidity low by heating or venting
  • Immediately remove any diseased plants from the area

Establish an Effective Fungicide Rotation

An ideal fungicide rotation program includes products with modes of action in different FRAC groups. This will maximize the strength of each product and help mitigate resistance development. Subdue Maxx® and Mural® fungicides are two foundational products of a solid rotation program for Pythium.

Subdue Maxx, powered by an active ingredient in FRAC Group 4, protects roots and stems against Pythium spp. and Phytophthora spp.

Mural fungicide is powered by two active ingredients in FRAC Groups 7 and 11 to protect ornamental crops against Pythium spp., as well as other soilborne pathogens such as Rhizoctonia solani. Mural also provides plant-health benefits such as enhanced root development.

Take Advantage of the Best Savings

Make sure you have a plan in place and the appropriate products to protect against Pythium and other cool-season diseases for the rest of the year. Lock in your yearlong product rebates by making your qualifying purchases during the GreenTrust® 365 Early Order Period, now through Dec. 8.

With the enhanced Double Up Bonus, expanded Multipaks and more, you can get the best savings of the year on over 25 trusted brands.

All photos are either the property of Syngenta or are used with permission.

© 2023 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. GreenTrust®, Mural®, Subdue Maxx® and the Syngenta logo are trademarks of a Syngenta Group Company.

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