We all know that with the rain showers the weeds are going to start to appear in our grass soon if we don’t take some action. The best approach for early season weed issues is to down a pre-emergent and with temperatures that will be on the rise soon.  There is no better time than in the next few weeks. I will be outlining the specific steps needed to take action before the weeds become an issue.

Normally when we have this cold of a year the weeds will emerge a little later than normal from the heavy freeze but with timely rains and some warm weeks we’re starting to see quite a few annual weeds appearing. If you live south of Tucson or up north where you are still getting morning frosts you can hold off on weed control until the end of the month, but for the Phoenix and Palm Springs area now is a great time to get this product down.

Before we precede any further into this topic it is important for you to take a close look at the bag of fertilizer with weed and feed and use the rate for the type of grass you are currently growing. If you overseeded your lawn this fall then you will be using a much lower rate than those that left their lawn dormant for the winter. You can cause some serious damage to your lawn if you’re not careful with a selective herbicide.

Many people are nervous about using a pre-emergent because they have burned or done damage to their lawn in the past but if you follow the directions and don’t exceed the labeled rates your grass will thrive this spring. I want to clear up any misconceptions regarding pre-emergent so you’re not disappointed with the results if you’re already seeing weeds present.

  1. Pre-emergent’s don’t kill weeds and seeds that are present, they keep them from growing.
  2. The timing of the application is just as important as the rate and I’m taking the guess work out of it for you. The soil temperature is currently above 50 degrees which is optimal for the application and the next couple weeks is the most critical time to make this application.
  3. I know a lot of people who would prefer to keep their lawn organic and not apply a herbicide and while you’re not going to get as good of results you can keep the weeds to a minimum with applications of Corn Gluten. Mixed results have been shown with this product, but it has been known to be effective against the emergence of barnyard grass, lambs quarter, and crabgrass.  See the label for application rates and timing.
  4. Weeds will often attack the weak areas of your lawn so if you have bare spots you can expect that these are the first areas that weeds will emerge. Having a healthy lawn reduces a weeds ability to get into your lawn and grow. If you’ve let your grass go dormant for the winter you can expect to see some weed activity because there is no competition between the weeds and the turf.

Pre-Emergent Weed Control

There are so many herbicides on the market today that treat any number of weeds but I have provided a list of the herbicides I’ve had the most success using. This doesn’t mean that a product I didn’t name won’t be effective but unfortunately some of the others I have not done enough testing on.

  1. Barricade 65WG (Prodiamine)
  2. Dimension (dithiopyr)
  3. Ronstar (oxadiazon)
  4. Pendulum (pendimethalin)

Post-Emergent Weed Control

  1. Trimec Classic for bermudagrass overseeded with ryegrass.
  2. Trimec Southern for paspalum lawns overseeded or not overseeded with ryegrass.
  3. Vanquish (Dicamba) Safe for bermudagrass and paspalum overseed/Non
  4. 2,4-D Amine – Safe for bermudagrass lawns overseeded/Non
  5. Xonerate (Amicarbazene) – This can safely be used on ryegrass to control Poa Annua in a bermudagrass or paspalum overseed/Non.  See label for rates. Best used in two half rate applications split up a month apart.

Before making an application of a pre-emergent herbicide make sure you take a look at the following:

  1. Irrigate afterwards, water activates pre-emergent herbicides.
  2. Measure your lawn surface area and calibrate your spreader properly prior to application. Applying more herbicide than is necessary could cause damage to your lawn.
  3. If you are starting to see a little emergence of crabgrass or Poa Annua after the product has been applied it is okay to make a second application of some products over the missed areas. Consult with the label prior to making a second application.
  4. If you have recently installed your turf (within the last 3 months) you should withhold all pre-emergent herbicide applications so you do not damage the root system.

It is extremely important to error on the side of caution when using any herbicide. Using more product than the label states is not only against the law it can also be very harmful to the turf. If you over apply herbicide you can expect to see residual damage for a few months after the application.

If you have a dormant lawn and are looking to get rid of Poa Annua before the bermudagrass or paspalum season apply Revolver, Kerb, or Certainty to remove.

Spring watering and fertilizing guide

Water your overseeded lawn 2x per week for 20-30 minutes. Ryegrasses root systems are fairly shallow and do not need to be watered as deep as bermudagrass.

Water a non overseeded lawn once per month in the month of February and 2x per month in the month of March. Your lawn will begin to green up in late march if the soil temperature is in range.

Fertilizer – Continue to foliar feed once per month with Soil Burst 7-7-7, Soil Burst 4-0-6, or Soil Burst 16-0-4.  I like to alternate between these three products to maintain consistency and a proper nutrient balance in my lawn.

Please let me know if you have any questions!