Preventing large patch in lawns

Now is the time to effectively control large patch to prevent widespread damage through the winter and next spring.

• Grasses affected – Previously, large patch was only thought to affect zoysia (once called zoysia patch), but we now know it affects all warm-season turfgrasses including seashore paspalum and bermudagrass
• Favorable conditions – Optimal conditions for large patch development include cool-to-mild temperatures (50-86°F) coupled with high soil moisture and extended periods of overcast weather. Though, like all pathogens, some activity may still occur outside of this range of environmental conditions
• Cultural management:
  • Aeration - Improved soil drainage and regular summer aeration is effective in reducing large patch
  • Nitrogen - Recent research (Miller et al., 2016) showed 0.75 lbs N/1000 sq ft applied in fall or spring to zoysiagrass did not increase large patch, in contrast to older information. Instead, positive turfgrass responses from N were found to occur on ‘Meyer’ zoysiagrass in spring, and the net result was a reduction of large patch symptoms
• Control with fungicides:
  • DMI fungicides – The preferred mode of action for soil-borne pathogens like this
  • Envu solutions – Armada^® applications should begin in the fall as the 2” soil temperature drops to 72-75°F, with a second application 28 days later. In extremely high pressure lawns, a third and final Armada application should be made in the spring when turf green-up reaches 50%
  • Apply in a minimum of 2 gal/1000 – Recent research at University of Tennessee indicates fungicides only need to penetrate as far as the leaf sheath to be most effective, so apply in high water carrier volumes or apply ONLY 0.1” or less irrigation after application when using a lower water carrier volume
• Need more info? Always read and follow label directions, see linked Solution Guide for more information, and contact your Envu Area Sales Manager if you need assistance.

Solution sheet - Large Patch

Large patch symptoms in a St Augustine commercial lawn (Envu).