Last week it was raining and in the low 60’s and this week we will be pushing the low 80’s. Everyone knows that the rain is great for our lawns but it is also great for producing weeds.

As we move through February it is important to think about your lawn from the previous year. Did you have weed issues? Were you constantly pulling spurge out of the lawn during the summer? Even if you didn’t have a bad case of this last year you should still think about putting down a pre-emergent herbicide. The window to apply these is from now until the end of February. If you miss the window and the seedlings have already germinated you can bet you will be on your hands and knees this summer pulling weeds out of your turf.

 

Weed infestations can be vicious especially if you have any voids in your grass. Weeds are naturally drawn to areas with very little competition so if you have open areas with dead grass or poor irrigation you should expect them to find their way into the grass.

There are a few options to controlling these and the first is to maintain a healthy balanced lawn. The second is to apply pre-emergent fertilizers, and the third is to treat weeds that pop up with post-emergent herbicides or by hand picking them.

Most people don’t want to deal with an invasion of weeds in their lawn so the easiest and most efficient way is to apply a pre-emergent herbicide. A pre-emergent herbicide is just that; it needs to be applied before the weeds emerge. It will not kill any weeds that are present in your turf.

After you have decided if you plan to pre-treat the weeds in your lawn you want to do some research on the products. Since it is February most of you will have an overseeded lawn so you need to check the label for the overseeded rate. If you currently have dormant lawns then check the label for your application rate. These rates may be the same but in general the overseeded rate will be lower than the non-overseeded rate.

Many homeowners would rather avoid using herbicides on their lawn which leaves a couple of options. The first is to apply corn gluten which works inhibits weed seeds from rooting into the ground. Corn gluten will control a number of weeds but you may not see the same results you would with a pre-emergent herbicide. Often times if you use corn gluten you will have a few weeds here and there break through the barrier so hand picking them will be necessary. If your lawn is healthy and null of any voids the corn gluten should help keep most weeds from invading your turf.

Pre-Emergent Weed Control

Here is a small list of some of the more popular pre-emergent herbicides on the market for bermudagrass and paspalum and they can be picked up at most specialty stores and used safely. Some of these do require a certified applicator to apply so you may want to contact a weed company to apply them for you. You will not be able to purchase the restricted use pesticides without a license. Many stores will carry their own generic brand of these chemicals but make sure you are getting the same active ingredient. If you cannot find one of these products in the store most of them are available online to ship to your door. Herbicides are generally not cheap but they are effective when used right so make sure you do some research.

• Barricade 65WG (Prodiamine) • Dimension (dithiopyr) • Ronstar (oxadiazon) • Pendulum (pendimethalin)

Before making an application of a pre-emergent herbicide it is important to follow the proper steps and always read the label.

• After you apply the herbicide, irrigate your lawn to activate the chemical. • Measure your lawn surface area and calibrate your spreader properly. • Do not over apply an herbicide hoping for better results. • Some products allow for a second application. Read the label first! • Newly installed lawns (within 90 days) should not use a pre-emergent.

 

Post Emergent Herbicides 

Post emergent herbicides can be used if you get in a pinch if a few weeds emerge from the turf or if you prefer to treat on a as needed basis. These chemicals will work to control weeds but you need to be careful when applying them. Never exceed the rates on the label and follow extreme care when using them. Too much herbicide can cause root damage to your lawn.

• Speedzone
• Trimec and Trimec Southern
• Battleship III (Not labeled in CA)
• Revolver (Poa annua removal. This product will also kill ryegrass so only use on dormant turf or during bermudagrass/paspalum growing season)

 

Fertilizer Recommendations

The air and soil temperatures are now warm enough to switch from foliar to granular fertilizers. It is okay to still spray your lawn once a month with foliar fertilizers but if it is easier for you to apply a granular now is a good time to do so. Most pre-emergent contain some fertilizer in the bag but you can buy some that don’t have any. For most people it is easier to apply one product but if you can’t find a product with fertilizer go ahead and make a second application. At this time of the year you will be very successful with any of the following products:

• Soil Burst granular 5-15-10 or any of the foliar products
•  Calcium Nitrate 15.5-0-0
• Turf Royale 21-7-14
• Ammonium Phosphate 11-52-0

You should always water in your fertilizer with 15-20 minutes of water so it completely breaks down and the plant can take up the nutrients.

Water Recommendations

Every lawn and irrigation system will vary in the length of time they need to be run, but you’re looking to water to a 6-8 inch depth. This can be checked with a screwdriver. If you can easily push it down 6-8 inches then your lawn is getting plenty of water. If it can’t penetrate the soil you will need to run more water. Soil compaction can be a real problem with our clay soils so if you can’t get a good watering without run off it is important to have your lawn aerated. This will allow for better infiltration and percolation.

Overseeded lawns should be watered no more than 2 days per week and non-overseeded lawns no more than once every other week until March. In March you can switch to once a week and then by April to a couple days a week. There is no point in wasting water on dormant turf that will not green up until late March when the soil temperature is warm enough.

Until next time,

Jay