Editor’s note: For an overview of pre-emergence weed control, we recently interviewed Laurence Mudge, technical services coordinator for Bayer Environmental Science.
Q: What are the benefits of a pre-emergence program versus post-emergence weed control?
A: There are several benefits to a pre-emergent program. First of all, pre-emergents are more cost effective, so you can spend less money on pesticides and labor costs. If you depend on post-emergent products, then you will be out there spraying whenever the weeds pop up. There’s a lot less hassle and a lot more weed control [with pre-emergents].
Q: What recommendations, in general, do you have for turf managers when selecting a pre-emergence herbicide?
A: Check the type of turf that you are treating, and then find out what types of weeds you are trying to control. For example, many treat for Poa Annua and broadleaf weed control in the fall. Before choosing a pre-emergent herbicide, make sure you know if the product is labeled for the turf you are treating.
Q: What advice do you have for turf managers who are faced with budgetary and/or time constraints when it comes to developing a weed control plan or program?
A: Turf managers need to look at the overall costs. Many turf managers think it is cheaper to only use the post-emergent product and they will skip using a pre-emergent. They don’t count in the labor costs, repeat applications and overall hassle of treating weeds post-emergent. You need to plan and look at the overall costs of controlling the weeds.
Q: What factors have the biggest impact on pre-emergence herbicide effectiveness?
A: The turf grass health can play a role. If you have a well-established turf, and it is in good condition, that can assist the pre-emergent herbicides. That is one of the most important things about weed control—the health of the turf. When you have healthy turf, you are asking a whole lot less of your pre-emergent herbicide. Other factors include rainfall, soil texture, soil moisture, and the competitiveness of the turf.
Q: What are your recommendations regarding timing of applications of pre-emergence products?
A: Pre-emergent herbicides need to be applied before weed seed germination. You have to know when your weeds germinate. This depends on where you are in the country, but generally the application should be between February and April. The further south, the earlier the pre-emergent herbicides should be applied.
Q: What problems on turf lead to the most weed problems?
A: Anything that is injuring or damaging the turf: poor drainage, shade, areas where you may have winter kill or disease. Anything that is affecting the turf and opening up the canopy leads to weed growth. Healthy turf is an important factor in weed control. Weeds pop up in areas where the turf isn’t healthy. In wetter years, there is more weed pressure as opposed to dryer years when weeds don’t germinate as much.
Q: What resources do you recommend for developing a weed control program?
A: One of the best places to go when developing a weed control program is to contact your local state university’s turf weed specialist. They will be able to assist you with the weeds that are relevant in your region. If you have questions that are more product specific, reach out to the company and ask for their recommendations.