Posts tagged crabgrass

In search of grubs, and how to treat crabgrass and arborvitae

Linn County Master Gardener, Claire Smith, wrote the following about three of the most frequently asked questions to the Linn County Master Gardener Horticulture Hotline. The HortLine is available to answer questions from 9 am.. to noon and 1-4 p.m. Monday through Thursday  and  9 a.m. to noon on Fridays at (319)447-0647.

 

    One of the commonly asked questions in the spring concerns when to apply pre-emergent crabgrass killer.  Master Gardener Susan Long has this response:  Typically, the blooming of the forsythia or the redbud is a good indicator of when to apply pre-emergent crabgrass herbicide.  Pre-emergents must be applied before the crabgrass germinates. Ground temperatures must be a minimum of 50 degrees. If the material is applied too early, crabgrass seeds that germinate late in the season will not be controlled.  If applied too late, some crabgrass will have already germinated.  In central Iowa, this is usually mid-April to May 1.  However, if the weather warms up early or stays cool longer, then adjustments must be made based on the conditions.  Having a thick, healthy lawn that is fertilized, watered and mowed certainly discourages the growth of crabgrass. 

    Susan also answered a question about arborvitae having brown leaves due to winter burn and whether it will recover and/or should be pruned:  Avoid pruning browned, burned areas from evergreen trees and shrubs in the early spring since these branches may still have viable buds that will produce new foliage when growth resumes.  The brown will eventually fall off.  If the buds did not survive, then prune dead branches back to living tissue.  The affected trees and shrubs should look much better by late June or July.  There is no need to fertilize affected evergreens.  However, if the weather this spring is dry, periodically water evergreens to encourage new growth and speed their recovery.

    Another caller wondered what causes a lawn to be torn up at night.  Lawns that have grubs attract raccoons, skunks, and crows which turn over large patches of turf in search of the grubs.  The best time to treat is early in the summer when insecticides have the best changes of working.  The entire lawn may not need to be treated, rather treat grub “hot spots” determined by observation or sampling.  Presently trichlorfor (Dylox or Bayer 24-Hour Grub Control) and Sevin are the fastest-acting, most effective homeowner insecticides for curative grub control.  These must be watered in completely after application.  In many cases it may be preferable to repair the damage through seeding or sodding without treating.  If the old, loose sod is still green it may reattach with adequate watering.

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Master lawn care

The following comes from Linn County Master Gardener Claire Smith:

 

                Did you remember to stop the mail and newspapers and let the neighbors know you’d be gone when you went on vacation this summer?  What did you do about your lawn?  If you planned to be gone for more than a week, did you have someone mow it for you?  How about watering it?  Vacationing during hot and dry July and August might mean you will need someone to water for you.

                During these hot days, sustaining your lawn is important. If you choose to continue watering, clay soils should get a good soaking weekly; sandy soils should be watered at least, ½” twice per week and growing lawns need one inch per week.  Watering early in the day saves water lost to evaporation and reduces disease problems.  Actually, you could just let the lawn go dormant for the rest of the season.  It will turn brown during this stressful period, but once the weather cools and fall rains commence, it should green up again.  There is still time to lay sod if you have a new lawn but it will require extra care.  Be certain the soil surface stays moist until the sod roots into the soil below.  Once rooted it will still need thorough although less frequent watering. 

                Do not fertilize dormant or non-irrigated lawns now.  Fertilization can cause damage and may even kill the grass. 

                Crabgrass may be starting to appear.   Now would be a great time to pinpoint its location on your lawn map making it easier to target pesticide application as crabgrass is usually eradiated in early spring.

                Mow grass at 3-3 ½” tall. Taller grass is more drought tolerant and better able to compete with pests.  A plus to warmer dryer weather is that you can mow less often.  Leave grass clippings where they fall.  They impart organic matter, nitrogen and earthworm food.

                Rules of thumb:  mow high, keep pests under control and choose proper watering patterns.

 

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Why aren’t you outside??

 

Another cold weekend has come and gone, but this week holds promise of spring warmth (finally!) 

The following information from Horticulturist Richard Jauron of Iowa State University Extension offers tips on spring gardening chores, now that the weather might finally cooperate:

It’s hard to beat springtime in the Midwest.  Soon the browns and grays of winter will be replaced by the greens, reds and yellows of spring. While spring is an enjoyable time, there are a number of outdoor chores that need to be done to enhance our yards and gardens. Important springtime chores include applying preemergence herbicides to lawns, dividing perennials, removing mulch from strawberries, pruning roses and many others. 

Applying Preemergence Herbicide to Lawn
The key to successful control of crabgrass in lawns is the correct timing of the preemergence herbicide application. Crabgrass seeds begin to germinate when soil temperatures reach 55 to 60 F and continue to germinate over several weeks from spring into summer. If the material is applied too early, crabgrass seeds that germinate late in the season will not be controlled. Normally, preemergence herbicides should be applied in early to mid-April in southern Iowa, mid-April to May 1 in central Iowa and late April to early May in the northern portion of the state.  The timing of the preemergence herbicide application will vary somewhat from year to year because of weather conditions. However, events in nature generally occur in a natural sequence. Preemergence herbicides should be applied when the forsythia blossoms start dropping or when redbud trees reach full bloom. Crabgrass seed germination typically begins after these events. 

Dividing Perennials
Early spring is an excellent time to divide asters, mums, hostas, daylilies, garden phlox and many other perennials. Dig up the perennials in early spring just as new growth begins to appear. Divide each plant clump into sections with a sharp knife. Each division should contain several shoots and a portion of the root system. Replant the divisions immediately. Keep the newly divided perennials well watered through spring and summer. Most newly divided perennials do not bloom well until their second growing season. 

Removing Mulch from Strawberries
To reduce the chances of frost or freeze damage, leave the mulch on as long as possible. Removing the mulch in March may encourage the plants to bloom before the danger of frost is past. Temperatures of 32 F or lower may severely damage or destroy open flowers. Since the first flowers produce the largest berries, a late spring frost or freeze can drastically reduce yields.

To determine when to remove the mulch, periodically examine the strawberry plants in spring. Remove the mulch from the strawberry planting when approximately 25 percent of the plants are producing new growth. New growth will be white or yellow in color. (If possible, the winter mulch on strawberries should remain until mid-April in central Iowa.) When removing the mulch, rake the material to the aisles between rows. If there is a threat of a frost or freeze later in spring during bloom, lightly rake the mulch over the strawberry plants.

Pruning Roses
The upper portions of modern roses, such as hybrid teas, floribundas and grandilfloras, typically winterkill due to exposure to low winter temperatures and drastic temperature changes. When the winter protection is removed from these roses in early to mid-April, gardeners should prune out the dead wood. 

Pruning roses is relatively easy. Live wood is green and has plump, healthy buds. When pruned, the center of the stem (pith) should be white. Dead wood is brown, has no live buds and has a brown or gray pith. When pruning roses, make the cuts at least 1 inch below the dead, brown-colored areas. Make slanting cuts about 1/4 inch above healthy, plump, outward facing buds; the slant being in the same direction as the bud. Remove the entire cane if there is no sign of life.  Also, remove any diseased wood. 

Because of our severe winter weather, modern roses often suffer a great deal of winter injury. Normally, the primary objective is to remove all dead and diseased wood and to save as much of the live tissue as possible. If the roses overwinter well, gardeners can prune out weak, spindly canes in the center. 

After a seemingly endless winter of shoveling snow and removing ice from sidewalks and driveways, working in the garden over the next several weeks is going to be a lot of fun.

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Home lawn care

      The following is from Master Gardener Claire Smith: 

 Remember a few years ago when the TV helicopter pilot upon seeing a tornado shouted, “I see it!  I see it!”?  That’s how I felt today when I finally saw my lawn.  While all of the snow did provide a great deal of insulation and protection for our plants, I’m so glad it has finally melted.  Robins are searching for worms and squirrels are scavenging for any unburied nuts. And, on St. Patrick’s Day, I did see a bit-o-the-green peeking through.

     Oh! How I want to get to work on the lawn right now.  My goal this year is a strong turfgrass stand.  An ISU bulletin titled Home Lawn Care:  Weed Control indicates that weeds in a lawn are often a sign of a thin turfgrass stand.  (FYI, Turfgrass is defined as a spreading or stoloniferous [a horizontal branch from the base of a plant that produces new plants from buds at its tip, called a runner] grass as opposed to a tufted grass.)  Maintaining a dense turfgrass stand prevents weed infestations so: 

  • Choose the correct species of turfgrass. Kentucky bluegrass grows best in full sun.  A mixture containing fine fescues is suitable for shady areas.
  • Routine mowing will eliminate weeds with an upright growth habit.
  • Mow at a 3-3 ½” height
  • Inadequate or too frequent irrigation damages turfgrass
  • Identify weeds to determine method of removal.  A visit with your weed sample in hand to your Extension Office (in Marion at 3279 7th Ave. Ste 140, in the professional building in the strip mall next to the farm store) will provide not only an identification of the plant, but a suggested eradication plan as well.

          Weeds can be mechanically removed by pulling or digging. Chemical weed control may be your choice using an application of pre and/or postemergence herbicides.  Most herbicides selectively kill certain weeds.  A second application 7-10 days later may be necessary.  Apply preemergence herbicides in Southern Iowa around April 10th and around May 15th in the North.  A guide for crabgrass control is application of the chemical by the time the forsythia blossoms begin to drop or when the redbud trees are in full bloom. Optimum control of broadleaf weeds occurs when postemergence products are applied during the plants’ early bloom stage.  2-4-D and DSMA will control certain weeds without injuring the turf grass. Early spring applications are safer as some products vaporize and drift under high temperatures and humidity potentially damaging flowers and shrubs.       Apply when air is calm and rain is not expected for 24 hours.Use proper caution when mixing or handling any pesticide.  Most products available consist of a prepackaged mixture of two to three chemicals.  I’m off to pick up branches that are no longer frozen to the ground and watch the critters that are enjoying the advent of nicer weather as much as I am.  Happy Spring!! 

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