Serious About Sod – Spring 2023
1. Cover Crops for Nursery Sod Production
Cover crops in sod production can be either sown in the fall or in the spring on recently harvested fields. For a cover crop to be of any use in nursery sod production, it must be quick to establish. Some of the benefits of cover crops are as follows:
· Reducing wind and water erosion of the soil
· Improve soil tilth
· Improve soil health
· Add organic matter
· Reduce nutrient losses
· Improve soil structure and reduce compaction
· Suppress weeds
· Conserve soil moisture
A. Fall Cover Crops After Sod Harvest
Sod fields harvested during the months of September and October will benefit from a cover crop that will survive the winter and continue to grow the following spring.
The best cover crop for this purpose is winter wheat, which can be planted from September until the end of October in most areas of Ontario. Use a seed drill to plant winter wheat at a rate of 90 lbs per acre. This is the preferable method of planting. Winter wheat can also be broadcast on the soil using up to 120 lbs/acre of seed spread and lightly disked in, or cultipacked to cover the seed.
Where Callisto herbicide was used in the sod crop, the residue should not be an issue when planting winter wheat. The winter wheat crop should be mowed down in mid- to late-June and worked into the soil. This will help break down the wheat residue, allowing the formation of a good seed bed to sow the field for nursery sod production in August.
B. Spring Cover Crop After Sod Harvest
For sowing in the months of April and May on bare fields, oats would be the best choice as a cover crop, using 50 lbs/acre planted with a grain drill. If broadcasting, apply 70-75 lbs/acre. This crop matures in 60 days and should be worked down before it produces seed.
By late May to mid-June, Buckwheat could also be used as a cover crop. This crop can be left to grow for about 6 weeks and must be mowed and worked down once flowering begins, to prevent this crop from becoming a weed. This crop is best planted using a drill. The seeding rate is 50 lbs/acre. If the seed is broadcast, a rate of 70-80 lbs/acre is required. Broadcasted seed must be harrowed or lightly disked into the soil.
2. The Effect of Temperature and Soil pH on the Loss of Nitrogen Sourced from Urea
Nitrogen from urea can be lost to the atmosphere if fertilizer urea remains on the soil surface for extended periods of time during warm weather.
The key to most efficiently using urea is to incorporate it into the soil during a tillage operation. You can also blend it into the soil with irrigation water. As little as 0.25 inches of rainfall is sufficient to blend urea deep enough into the soil so ammonia losses won’t occur.
A. Losing Urea to Air
Urea breakdown begins as soon as it’s applied to the soil. If the soil is totally dry, no reaction happens. But with the enzyme urease, plus any small amount of soil moisture, urea normally hydrolyzes and convers to ammonium and carbon dioxide. This can occur in two to four days and happens more quickly on high pH soils.
Unless it rains, you must incorporate urea during this time to avoid ammonia loss. Losses might be quite low in the spring if the soil temperature is cold.
B. Losing Urea Due to Soil Temperature and pH
Urea’s volatility depends to a great extent on soil temperature and soil pH. Tables 1 and 2 show that, after a few days, warm temperatures or high pH would cause losses.
Table 1 Impact of Temperature on Urea Losses
Table shows percent of surface-added urea volatilized as ammonia at different temperatures and days on the surface. Urea was added on a silt loam soil at 100 pounds of N.
Table shows the percent of surface-added urea volatilized as ammonia at various soil pH levels and days on the surface. Urea was added on silt loam soil at 100 pounds of N per acre.
The losses in this chart are in pounds per acre. The higher the soil pH and the higher the air temperature, the greater will be the loss of nitrogen when urea is applied on the soil surface. The charts are reproduced from information developed by the University of Minnesota Extension services.
3. Acelepryn Insecticide for Turf
This insecticide has been registered for 7 years. The active ingredient is Chlorantraniliprole and contains 200 g/L of active ingredient. The registration is for the control of the following insects:
In the past, we have used Sevin, chlorpyrifos (Dursban) and imidacloprid (Merit) to control many of these insects. Sevin usage has been severely restricted and chlorpyriphos is no longer available. Imidacloprid control has been variable (possible resistance). Acelepryn is from a different chemical family and must be used as a rotational product to prevent insect resistance.
For the control of our number one pest, European Chafer larvae, Acelepryn can be used from early April to early September. For the control of overwintering grubs in April, I would suggest using the higher rate of 800 ml/ha, since these grubs are large and harder to control. For the control of young larvae between mid-July to mid-August, the lower rate of 560 ml/ha is recommended.
4. Spring Checklist of Things to Watch For
Grubs can cause poor sod lift because of reduced root mass. Usually, this problem occurs in lighter soil types such as sandy loam. Grubs attract raccoons and skunks, which feed on them, causing damage to the sod. With the registration of Acelepryn, we now have a more effective insecticide for controlling larger grubs. Where roots have been weakened by grub feeding, either Triomax applied at 1.0 L/acre, or TruPhos Platinum at 0.67 L/acre can be applied using 2-3 applications -10 days apart to regenerate roots.
Check all fields for Gray and Pink Snow Mould. I have rarely seen either disease in nursery sod fields. Adequately feeding sod with potassium helps to increase tolerance to these two diseases.
Fairy Ring is becoming somewhat more common in sod fields. Where Fairy Ring is found, an application or two of Heritage (azoystrobin) will control this disease.
For broadleaf weeds, an application of Killex, Tri-Kill, of Par III will be effective. For the control of poa, bentgrass, and broadleaf weeds, Callisto is very effective. Conditioning the water with Disclose pH will improve the performance of these herbicides. With Callisto, adding Agral 90 at a rate of 2 litres per 1000 liters of water will also improve weed control.
At the end of May, all sod fields should be checked for compaction and aerated where required.
5. Other Notes
Always condition the spray water with Disclose pH to ensure that pesticide performance is not impeded by the hardness or pH of the water used. In most spray water used in Ontario, the average rate of Disclose pH is 2 liters per 1000 US gallons. We do have spray kits available to determine the rate of Disclose pH required.
For increasing the quality and the harvest of nursery sod, apply TruPhos Platinum @ 0.67 L/acre, or Terra Drive @ 1.0 L/acre. Terra Drive is compatible with all commonly used pesticides in turf. TruPhos Platinum is NOT compatible with phenoxy herbicides, such as 2,4-D, Killex, 3-Way, or Tri-Kill.
If you have any questions or need some advice, please contact me.
Joe Uyenaka BSc. Agr., CCA-ON Senior Agronomist, Nutri Ag Cell: 705-791-9321