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Understanding when to water-in plant protection products

To get the best performance out of any product application, there are many best management practices to consider. The focus of these recommendations is to review water movement into the soil, watering depth and product applications. Always check the product label for watering-in recommendations.

The objective of post-application water is to move the product to the source of the problem. This is especially true when controlling nematodes, fairy ring and summer patch.


Controlling nematodes with Divanem® nematicide is best achieved if Divanem moves into the soil where nematodes are most active. Applications with Divanem (at low use rates of 3.125 fl. oz.-12.2 fl. oz. per acre) are best made to wet turf. If dew is not present, use a short irrigation cycle to moisten the turf prior to application. The first watering-in option for Divanem is to irrigate with 0.25 in. of water within one hour of application. The second option is to irrigate with 0.125 in. of water within one hour after application, and another 0.125 in. of water within 24 hours.

Nematode-damaged roots not only absorb less water, but are also more susceptible to disease. When combined with Heritage® Action™ fungicide, Divanem can further improve turf quality, turf density, root growth and root quality, as well as provide enhanced biotic and abiotic stress tolerance. The Divanem + Heritage Action Multipak contains 0.5 gal. of Divanem and 5 lbs. of Heritage Action and provides convenience when applying these products together.
For more information about nematode control rates and scouting tips, visit www.GreenCastOnline.com/NematodeKnowledge

Fairy ring

When applying a fungicide for fairy ring control, it’s important to determine the depth of the fairy ring infestation. If fairy ring is limited to the thatch layer, irrigate with 0.1-0.15 in. of water following the fungicide application. If fairy ring is 2-3 in. deep, irrigate with 0.25 in. of water following the application. Repeated applications at regular intervals are needed to maintain consistent suppression in the soil.

For best results, Velista® fungicide should be watered-in soon after application. Applications of Heritage®, Banner Maxx® II, Headway® and Briskway® fungicides can be allowed to dry on the foliage, and then watered-in prior to the next mowing.

For more information about fairy ring control, view our fairy ring solutions sheet.

Summer patch

Summer patch is a root-infecting pathogen that affects annual bluegrass, Kentucky bluegrass and fine fescues. Since the pathogen is soil-borne, the immediate response is to water-in all fungicide applications. While this is true for Kentucky bluegrass and fine fescue, some caution needs to be taken with annual bluegrass on greens’ surfaces.

Watering-in fungicides like Heritage and Headway in the spring is recommended, as roots are actively growing and will be deeper during this time period. Applying 0.1-0.15 in. of water is often adequate to move the fungicide into the soil. The active ingredient in both products, azoxystrobin, is taken up by the roots for protection. However, during the heat of summer, it is common for annual bluegrass roots to die back.

In this case, apply either fungicide in 4 gal. of water per 1,000 sq. ft. This will move the fungicide to the surface inch where the active roots reside. If this volume of water is not achievable, water-in with 0.05 in. of water, or no more than a light syringe. If too much post-application water is applied, it may move the active ingredient below the active roots, lessening the fungicide’s protection.

For more information, view this article about application timing, products and rates for protecting turf against summer patch.

Watering-in recommendations are the same for insecticides. If control is for surface-feeding insects, don’t water-in. It is recommended to water-in products like Acelepryn® and Meridian® 25WG insecticides for white grub control. The key is to target the upper 1 to 2 in. of soil where the insects hatch and develop.

For more information about watering-in, or if you are unclear about whether or not to water-in a particular product after reading the label, contact your local Syngenta territory manager.

©2018 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. Divanem is a Restricted Use Pesticide. The trademarks or service marks displayed or otherwise used herein are the property of a Syngenta Group Company.