UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail: dfculbert@ifas.ufl.edu

February 11, 2004

Feature Article - for release the week of February 15, 2004

Dan Culbert - Extension Horticulture Agent

Time to weed, but wait to feed

Groundhog Day has come and gone, and despite locally warmer temperatures and the bloom on our oak trees, the prediction of more weeks of winter still applies. Since spring is close by, our office is preparing for an increase in questions on spring lawn care. So before you rush out to buy and apply the "weed-n’feed" products that seem to be everywhere, take a look at today’s column so you don’t end up with a bad situation.

Weed and feed products are, despite their claim - PESTICIDES. They also contain fertilizer nutrients that are used by our lawn grasses. I don’t recommend that homeowners use them because, as a pesticide, they must be used according to the label. And in our Florida Yards, conditions where they can be used correctly will rarely exist. Here’s why:

Weed and feed products are very difficult to apply at the correct rates for both the herbicide and the fertilizer. And if your spreader is not calibrated, you will have too much or not enough of one or the other material.
Our local turfgrasses can be damaged by using the wrong product on the kind of grass you have in your lawn. Products designed for Bahiagrass will have different weed killers than those labeled for St. Augustinegrass.
These products generally contain "pre-emergent" weedkillers, which should be applied at this time, but they also add nitrogen fertilizer. At this time of year, they will cause new succulent grass to take off, which can lead to winter kill if another cold snap visits our area.

I like to think of pesticides as medicine for the landscape. You don’t take medication unless you are sick, right? And like your mother and your doctor told you, good healthy living can often take care of many health issues. Likewise, pesticides are medicine for a sick landscape. For your lawn, following these basic rules will get most lawns growing without the need for pesticides:

mow grass high - 3 to 4 inches when you are done cutting.
water the lawn only when signs of drought appear - don’t irrigate by a time clock.
fertilize 2 or 3 times a year with a slow-release granular fertilizer, one pound of nitrogen per thousand square feet.

If you follow these rules and still need "lawn medicine" for weeds, preemergent herbicides are great to use. They prevent weed seed from growing before the problem occurs. That’s why this is a good time to apply herbicides to your lawn, before the weed show their ugly leaves in your grass. In some cases, herbicides are the only reasonable way to manage weeds in sick lawns. But be sure you use the right tool - in this case, the right herbicide for the weed and grass. But if you wait too long to apply them, they will either damage your lawn or fail to work on the weeds.

A general rule of thumb for preemergent herbicides is to apply them around February 15^th in central Florida, when day temperatures reach 65 to 70 degrees F for four or five consecutive days. (These applications generally occur with the blooming of landscape plants such as azalea.) Be sure that enough soil moisture is present before and after application - water is necessary to activate most preemergent herbicides. Preemergent herbicides don’t last forever - expect 6 to12 weeks of relief - and by that time the grass should be able to outgrow any weed that occurs in summer lawns.

Is that weedy area being treated next to your shady oak tree or your delicious citrus tree? Here’s another word of caution - weed and feed products should be used with caution near ornamentals. Products that contain dicamba, metsulfuron, or atrazine can be absorbed by the roots of ornamentals and cause severe injury. The pesticide label will say, "Do not apply products that contain these ingredients near the root zone of ornamental trees and shrubs."

And a final word of caution - it is illegal for a landscaper or yard man to apply these products for you unless YOU buy the product and loan them YOUR spreader or sprayer. Only those pest control companies with a valid pesticide applicators license may legally apply any pesticide to turfgrass in Florida.

Master Gardeners can answer your questions about your Florida Yard - call or visit them on Tuesday afternoons here at our office. If you need additional information on landscape weed management, visit our webpage at http://okeechobee.ifas.ufl.edu , or stop by our office at 458 Hwy 98 North. Our phone number is (863) 763-6469, and you can email us at okeechobee@ifas.ufl.edu .

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. Florida Cooperative Extension Service / IFAS /University of Florida. Larry A. Arrington, Acting Dean.

References

Trenholm, Laurie. Home Lawn Care - Chemical control. (webpage) UF/IFAS Extension Service, Department of Environmental Horticulture, 2004 http://turf.ufl.edu/residential/weedchemical.htm

Unruh, J.Bryan, Brecke, Barry, and Trenholm, Laurie E. Weed Management in Home Lawns ENH884 Gainesville: UF/IFAS Cooperative Extension Service, March 2003. http://prohort.ifas.ufl.edu/pubs/EP141.pdf

Unruh, J.Bryan, and Brecke, Barry. Response of Turfgrass and Turfgrass Weeds to Herbicides ENH-100 Gainesville: UF/IFAS Cooperative Extension Service, January 1998. http://edis.ifas.ufl.edu/WG071

UF Herbicide recommendations are included in the University of Florida's Pest Control Guide for Turfgrass Managers. Since pesticide labels change rapidly, do not use this information after 2009. To see a list of products for Homeowner weed control, click here.

Consult your County Extension Agent if you need help selecting the right product.

Last update: 07/30/2009 . This page is maintained by Dan Culbert