Spring and Lawns Care in Home
What is Spring Dead Spot?
Spring Dead Spot is probably the most destructive Turf pathogen affecting bermudagrass turf. The causal organism of Spring Dead Spot is Ophiosphaerella, a soil-borne pathogen considered to be indigenous to most southern United States soils. Three species of Ophiosphaerella have been identified (korrae, herpotricha and narmari) with korrae being the most common to our area. Spring dead spots are generally round in shape and can range from 6″ to 1′-2′ in diameter, but in severe cases, the spots will coalesce into large, irregular patches. The infected turf is actually dead as the name suggests and will have to be replaced or encouraged to fill in from the edges.
Weak turf that is under stress from, agronomic, physical, or climatic factors is especially vulnerable to Spring Dead Spot. This may be why we have seen so much of it this spring due to the harsh wet, cold winter we had. The pathogen infects the turf’s root system in the fall eventually causing the plant’s vascular tissue to clog preventing the normal flow of water and nutrients. Over the course of the winter, when the turf is dormant, there are no symptoms evident and everything appears normal. In the spring though, as the weather begins to warm, the infected turf is unable to draw upon reserves of water and nutrients to break dormancy. Some affected turf may appear to green up as healthy turf would, but it quickly declines as the plant is starved for energy from the clogged vascular tissue.
Research to this point has not found a consistent cure for this disease. However, a preventative management approach incorporates a wide range of cultural, agronomic, and chemical control techniques. Factors to consider include but are not limited to mowing height, fertility, aerification, thatch management, pH, and fungicide use.
Slow spring turf growth and association with the 150 Rule
Most warm-season grasses have been slow this spring to transition from winter dormancy to active growth. While we may be somewhat eager and impatient to see our lawns, sports fields, golf courses, etc. turn from their winter brown to a healthy, solid green, it just will not happen until we have temperatures that are much more conducive to warm-season turf species growth.
A rule-of-thumb guideline that many of us use to predict when our turf will really get active is the 150 rule. This rule is derived by taken the night time lowest temperature and adding it to the daytime high. The sum of which should be near or above 150. As we look back to the month of April we had some very nice warm sunny days with day temperatures reaching into the high 70’s and low 80’s. However, the nighttime lows most often were in the ’40s or lower 50’s making the sums of the highs and lows far from the optimum 150 or higher. Therefore, we must just remain patient and look forward to warmer temperatures which will soon provide our turf conditions much more favorable for active growth.
Lawns First Mowing of Spring
Spring is only a few weeks away. Many homeowners are anxious to mow flowering winter annual weeds and to remove much of the old dead leaf canopy from the previous summer. I receive several calls each spring asking if a lawn can be burned or mown very low (scalped) in early spring and the reply is yes but with reservations and restrictions.
I strongly discourage burning. This practice is usually not very uniform, the liability risk is great, it creates smoke and soot to deal with, and many communities have ordinances that forbid burning.
Lawns of bermudagrass or zoysia can be cut very low (scalped) since they have a strong network of rhizomes (below soil runners) and stolons (above ground stems) that will quickly replenish the turf canopy with new rejuvenated growth if soil and air temperatures are warm enough for growth. Centipede and St. Augustine lawns can also be cut slightly lower than their optimum mowing height but should not be “scalped” as they have only stolons to develop a new canopy. Scalping or close mowing should not be a continuous process throughout the season but only once when the lawn begins its initial spring growth.
Since there will be an excess of old clippings being removed, this may be a time to collect clippings rather than leaving them on the lawn. They then should be utilized as compost and not considered trash to fill our landfills.
Lawn spring transition mowing (scalping)
There are advantages and disadvantages to mowing your lawn below the optimum growing height (scalping) as it breaks winter dormancy.
A close mowing now and collecting the clippings will remove the heavy winter canopy allowing quicker soil warming to hasten the spring transition and eliminate excess thatch. It will also eliminate many winter annual winter weeds, or at least prevent them from producing a seed supply for next fall. If there are poor drainage areas that need leveling, scalping in early spring will make it much easier to spread the soil where it is needed.
There are disadvantages as well, however. If a pre-emergence herbicide was not applied, opening the turf canopy when summer annual weeds are germinating will invite a greater weed problem this summer. Scalping may also set the lawn up for winter injury from a late spring freeze, especially those turf species such as St. Augustine and centipede that have only stoloniferous growth and are more sensitive to cold.
For most lawns, scalping is not needed and is simply a waste of time. Scalping is not a recommended practice once the turf has completed the spring transition. A normal mowing regime of maintaining the turf species optimum mowing height and removing no more than one-third the total leaf area at a single mowing should be followed throughout the growing season.
Spring Lawn Diseases are Enhanced by Fertilizer and Leaf Wetness
Many Southern lawns have their greatest incidence of turf disease pressure during spring transition. This pressure is often enhanced by fertilization and leaf wetness. If your lawn has a history of spring turf diseases, particularly large patch, then be careful not to over-fertilize your lawn during the next few weeks. In fact, if you applied fertilizer to the lawn late last summer you could probably wait until mid-May before applying any this year. Fertilizers with readily available water-soluble nitrogen sources that stimulate excessive lush growth tend to create the greatest potential for lawn diseases. Therefore, it would be a better choice to select a fertilizer that has at least some of the nitrogen source in water-insoluble (WIN) form.
Leaf wetness along, with the lush growth from the fertilizer, no doubt is an invitation for turf disease flare-ups. We can’t prevent leaf wetness caused by Mother Nature, but we can manage our watering regimes to limit the length of time the grass foliage remains wet from irrigation.
When is the best time of day to water my lawn?
Early morning between 3:00 and 10:00 is considered the ideal time. The reason being that the less time the foliage is wet the lower the incidence of disease. Generally by 3:00 a.m. the foliage is wet anyway from dew or exudates from the leaves and it takes until about mid-morning for this to dry. The worst time to water is just before nightfall as this will prolong leaf wetness for the entire night. Now I don’t expect many of us to get up at 3:00 a.m. to water our lawns, but hopefully, we can find some time early enough in the day to allow the leaves of the grass to dry before nightfall. It is also better to water thoroughly only once or twice a week than to apply small amounts daily.
Large patch is most prevalent spring disease of Southern Lawns
The fungus (Rhizoctonia solani) commonly known as a large patch (also referred to as a brown patch) is the most troublesome lawn disease for many lawns. While this disease attacks most lawn turf species, it is most serious on St. Augustine and centipede lawns in the spring and fall.
Large patch is most severe when temperatures moderate at night in the upper 50 and 60-degree range with midday temperatures in the 70’s and low 80’s. Once summer temperatures get into the upper 80’s and higher disease activity ceases until fall. Visual symptoms are brownish to gray irregular circular patches often with a narrow smoke-colored ring bordering the diseased area. These water-soaked or scalded spots can spread rapidly from a few inches to several feet in size. The fungus generally attacks the base of leaf sheaths where they join to the stolons. When the disease is most active, infected leaves may slip easily from the stolons when pulled on and display a brown, wet, slimy decay at their base.
Large patch activity is enhanced by high nitrogen fertilization, moisture on the leaf surfaces, and excessive thatch. Therefore, to diminish the incidence of attack, be judicious with spring fertilization, particularly with fertilizers high in water-soluble nitrogen. Water early enough in the day to allow foliage to dry before nightfall. And maintain good mowing practices to manage thatch buildup.
Warmer Spring Weather has Increased Mole Activity
Many homeowners have recently noticed an increase in raised ridges of soil across their lawns in somewhat erratic patterns. These ridges are caused by the shallow tunneling of moles in search of food which is mainly earthworms, beetles, grubs and other insect larvae.
The soft, moist soil from winter rains, followed by warmer temperatures, brings insects and worms closer to the surface and really gets these small critters on the move to satisfy their voracious appetites. While they rarely feed on plant material, their tunneling can cause damage to the roots of turf, bulbs, etc.
Moles are small, furry critters with beak-like noses and tiny rudimentary eyes. They have no visible ears, paddle-like front feet with large claws and stubby, hairless tails. In controlling moles just remember the reason they are there is because they are finding something to eat and if the food is not there, then they will eventually leave.
Repellants, such as caster oil, may deter them from using tunnels that it is applied into but does not stop them from making new ones. There are several effective poisonous bait products available, but caution must be taken in using these where other small animals may come in contact with them.
One product containing the active ingredient warfarin, an anticoagulant and simply called , is packaged similarly to a caulking tube that injects the gel into the tunnel. As the mole crawls through it he gets the gel on his face and feet which he attempts to lick off and ultimately is poisoned. Another true bait type product with the active ingredient bromethalin is shaped, textured, and even smells and taste similar to earthworms. Apply by poking a small hole into the main tunnel then drop one of the earthworms shaped baits down into the tunnel. This product is marketed as Talpirid and other trade names.
Trapping is still the homeowner’s most cost-effective and safest method of removing moles if you do not want to harm your beneficial earthworms or have concerns about pets and wildlife. However, trapping requires some skill, lots of patience and general knowledge of mole habits. A harpoon trap can be purchased from most garden centers. Early spring is usually the best time of year to trap since the moles are active very close to the soil surface and the soil is cool and moist. Not all tunnels are traveled regularly, so it is important to find the main daily run. This is accomplished by simply making a step on the tunnels to firm the soil back down and checking each morning to find which tunnel is used daily, then set the trap on that tunnel. If you are not successful after a couple of mornings reset the trap in another location.
Moles, soft soil, and spring weather
Moles are small furry critters described as having beak-like noses, tiny rudimentary eyes, and no visible ears. They have paddle-like front feet with large claws and stubby, hairless tails. The soft moist soil from winter rains followed by warmer weather of spring really gets these small critters on the move to satisfy their voracious appetites.
The ridges seen in many lawns are caused by their shallow tunneling in search of food which is mainly a diet of earthworms, beetles, grubs, and other insect larvae. While they rarely feed on plant material, their tunneling can cause damage to the roots of turf, bulbs, etc.
In controlling moles, just remember the reason they are there is because they are finding something to eat. If the food is not there then they will soon leave. Repellants such as caster oil may deter them from using tunnels that it is applied, but it does not stop them from making new ones.
There are several effective poisonous bait products available, but caution must be taken in using these where other animals such as cats, dogs, squirrels, etc. may come in contact. One material called with the active ingredient warfarin, an anticoagulant, is packaged similarly to a caulking tube. It injects the gel into the tunnel. As the mole crawls through, it gets the gel on its face and feet and is poisoned when it licks it off.
Another bait type product, with bromethalin as the active ingredient, is shaped, textured, and even smells and tastes similar to earthworms. You simply make a small hole into the tunnel and drop one of these earthworm type baits into the tunnel. It is marketed as Talpirid and other trade names.
Trapping is still the homeowner’s most cost-effective and safest method of removing moles if you do not want to harm your beneficial earthworms. However, trapping requires some skill, a lot of patience, and general knowledge of mole habits.
A harpoon trap can be purchased from almost any garden center. Early spring is usually the best time of year to trap since the moles are active very close to the soil surface and the soil is cool and moist. Not all tunnels are traveled regularly, so it is important to find the main daily run. This is accomplished by simply making a step on the tunnels to firm the soil back down and checking each morning to find which tunnel is used daily, then set the trap on that tunnel. If you are not successful after a couple of mornings reset the trap in another location.
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