Is your business ready for the start of another season? What challenges is your business going to face in 2024? What opportunities do you see within your business in 2024? While many are still in the heart of Winter across the U.S., our busy season is just around the corner. It is vital to take the time to think about these questions and plan for the upcoming season. One of the most urgent tasks for many lawn care operators (LCO’s) to kick off the entire season is planning their pre-emergent herbicide program. Your answers to the initial questions above, may help lead you to a product that matches your program and business goals.
Regardless of what pre-emergent product you decide to apply this Spring, the pre-emergent application is so important for the success you are seeking this season. Whether you are an applicator or the business owner there is one opportunity to set your season off in the right direction with a solid pre-emerge application. It can truly define what the road ahead will look like for your business and customers lawns.
When it comes to pre-emergent herbicides in the market the two products that often come to mind and are used most often are Dimension (Dithiopyr) and Prodiamine (multiple trade names). This article serves to compare these two pre-emerge active ingredients and guide you in making an informed decision on which product choice may be best for your program while aligning to your business goals.
Both Dimension and Prodiamine are available in liquid, wettable powder, and on combination fertilizer formulations that will fit a preferred application method of your choice. A potential negative characteristic of Prodiamine is that it causes yellow staining to equipment and/or the application site. Dimension is a non-staining formulation.
Mode of Action (MoA)
This is a good time for a major point of clarification. You may have heard about “rotating” Dimension and Prodiamine every so often to “change the chemistry up”. Rotation of chemistries comes into play when trying to avoid resistance (which is important), but in the case of Dimension and Prodiamine they are both Group 3 Herbicides. Therefore, just switching from Prodiamine to Dimension or Dimension to Prodiamine is not rotating the MoA. Where there is some separation is in their chemical families. Prodiamine is a Dinitroanaline (DNA) and Dimension (Dithiopyr) is a Pyridine. This difference does separate the two active ingredients as you will see later in the article.
For Prodiamine the maximum application rates will vary depending on the type of turf but in general cool season turf species are in a range of 10-24 fl. oz per calendar year where as warm season turf species in the 21-48 fl. oz per calendar year. Please always refer to the label for specifics. This leaves the ability for ~2 applications (depending on rate) per year. Dimension’s rate range across almost all cool and warm season grass varieties ranges from 1-2 pints/acre per application with no more than 6 pints/acre per year allowed (~3 applications, depending on rate).
Both Prodiamine and Dimension will inhibit the development of turfgrass when overseeded to soon after an application. For Prodiamine applications in Northern cool season turf predominate areas this interval can be anywhere from 4-6 months depending on the rate. In warm season turf predominate areas this range will vary even more greatly because of the higher and broader rates with reseeding intervals of up to 4-12 months. Dimension has reseeding intervals of 3-4 months depending on whether applications were made as a single application or sequential applications. This is very important to consider depending on the longevity of your season and re-seeding programs.
Watering-In and Activation Periods
All pre-emergent products need to be incorporated with water at some point to become activated in the soil. This activation period can be very different among the pre-emergent active ingredients on the market. Beyond Prodiamine and Dimension this is important to consider when making any of your pre-emergent product selections especially if you are relying only on natural rainfall to do so. Prodiamine labels will state that weed control is most effective when activated by at least 0.5 inch of rainfall or irrigation before weed seeds germinate and within 14 days following application. Dimension labels state the product is most effective when activated by 0.5 inch or more of rainfall or irrigation and to optimize control ensure that activation has occurred prior to germination of most grass and broadleaf weeds. While the goal is to get both these products watered in sooner rather than later so they can begin working for your program just note there is no actual hard deadline to get Dimension water in. This could be an advantage in areas where natural rainfall is scarce or difficult to plan an application around.
When we think of Dimension and Prodiamine the first thought is pre-emergent control for crabgrass. We will dive into that shortly, but I always like to remind LCO’s that these products also pre-emergently control many other grasses and small seeded broadleaf weeds. Dimension will have a slightly broader weed spectrum compared to Prodiamine in what it controls pre-emergently and is important to consider in your program. Now let’s address the big topic- Crabgrass. Both Dimension and Prodiamine are very effective at controlling crabgrass pre-emergently when properly applied and at the correct rates. Where Dimension begins to separate itself from Prodiamine is Dimension’s ability to not only control crabgrass pre-emergently, but also at an early post stage. In cool season turf predominate areas early post-emergent control of crabgrass can be obtained up to the 5 leaf stage. In areas where warm season turf species are predominating Dimension has demonstrated post-emergent control of crabgrass through the 3-5 tiller stage. Dimension’s ability to provide pre and early post- emergent control of crabgrass gives tremendous flexibility in your program and is a major advantage for Dimension applications in the Spring. What do I mean by flexibility? Prodiamine must be applied and activated prior to Crabgrass germinating (because it only has pre-emerge activity). In some areas this can be a very limited window to get the product out in time as soil temperatures warm up. However, because of Dimension’s pre-emerge and early post emerge control of crabgrass the application window broadens significantly for your business.
At the end of the day, both Prodiamine and Dimension are very effective pre-emergents for controlling crabgrass when properly applied. However, I challenge you to think about your individual business and think about the pain points you face when trying to get your pre-emergents applied each Spring. Next, match the pre-emerge that helps solve or alleviates those pain points based on some of the technical points featured in this article. At Central Turf and Irrigation, our team of subject matter experts are here and ready to guide you towards solutions to support both your agronomic and business goals in 2024.
*Please carefully read and follow all label instructions