Larry Crouse/K-State Extension/guest columnist

Crabgrass preventers are another name for preemergence herbicides that prevent crabgrass seeds from developing into mature plants. Crabgrass preventers are just that - preventers. With few exceptions they have no effect on existing crabgrass plants, so they must be applied before germination. Additionally, preventers do not last forever once applied to the soil.  Most crabgrass preventers are fairly ineffective after about 60 days, but there is considerable variation among products. For our part of Kansas, crabgrass typically begins to germinate around April 10th.  April 1st  is normally a good target date for applying preventer because it gives active ingredients time to evenly disperse in the soil before crabgrass germination starts. However, this year, we may want to go a week or two early.  For our area it is best to get it down as soon as you. Even better, base timing on the bloom of ornamental plants. The Eastern Redbud tree is a good choice for this purpose. When the trees in your area approach full bloom, apply crabgrass preventer. A follow-up application will be needed about 8 weeks later unless you are using Dimension or Barricade. Products that do require a follow-up application include pendimethalin (Scotts Halts) and Team (Hi-Yield Crabgrass Control).  Dimension and Barricade are the only two products that give season-long control of crabgrass from a single application. In fact, they can be applied much earlier than April 15 and still have sufficient residual strength to last the season. Barricade can even be applied in the fall for crabgrass control the next season. Dimension can be applied as early as March 1. Because of the added flexibility in timing, these products are favorites of lawn care companies who have many customers to service in the spring. Though Dimension is usually not applied as early as Barricade, it is the herbicide of choice if it must be applied later than recommended. It is the exception to the rule that preemergence herbicides do not kill existing weeds. Dimension can kill crabgrass as long as it is young (two- to three-leaf stage). Dimension is also the best choice if treating a lawn that was planted late last fall. Normally a preemergence herbicide isn’t recommended unless the lawn has been mowed two to four times. But Dimension is kind to young tall fescue, perennial ryegrass, and Kentucky bluegrass seedlings and some formulations can be applied as early as two weeks after the first sign of germination. However, read the label of the specific product you wish to use to ensure that this use is allowed. Lawns established in the fall can be safely treated with Dimension the following spring even if they have not been mowed.  Note that products containing Dimension and Barricade may use the common name rather than the trade name. The common chemical name for Dimension is dithiopyr and for Barricade is prodiamine. Remember, when using any pesticide, read the label and follow instructions carefully. We recommend crabgrass preventers be applied before fertilizer so that the grass isn't encouraged to put on too much growth too early. However, it’s difficult to find products that contain preemergents only. Those that don't contain fertilizer are listed below.
Pendimethalin  - Scotts Halts,
Team (Benefin + Trifluralin)  - Hi-Yield Crabgrass Control
Dimension  - Hi-Yield Turf & Ornamental Weed and Grass Stopper  - Bonide Crabgrass & Weed Preventer  - Green Light Crabgrass Preventer
Asparagus Time      
Asparagus is one of those vegetables where freshness is incredibly important. If you have never eaten asparagus fresh out of the garden, try it. It may convince you to grow some of your own. For those who have an asparagus patch, the new spears should be appearing soon. The first asparagus that comes through the ground always seems to take a long time to reach harvest size. That is because asparagus growth is temperature dependent. The higher the day and nighttime temperatures, the faster it grows. Also, the longer the spear, the quicker the growth. As the season progresses and spears get longer, the growth rate increases. Harvest asparagus by snapping or cutting. Snapping is quick and easy. Simply bend the stalk near the base until it breaks. Snapped ends dry quickly so refrigerate or use soon after harvest. If you cut asparagus, use a sharp knife to detach the spears slightly below ground level. This base is woodier than snapped asparagus, so it doesn't lose water as quickly. Cut off woody ends before cooking.
So, how long can asparagus be harvested?  Do not harvest at all the year of planting.  The next season, harvest for 3 to 4 weeks or until the spear size drops off.  Every year thereafter, the asparagus can be harvested for 6 to 8 weeks.
Frost Proof Vegetable Plants     
Certain vegetables can withstand cold spring temperatures as long as they have been toughened up by gradually exposing them to sunlight and outdoor temperatures. This "hardening off" process usually takes about a week. Reducing watering and temperature is the key to toughening up transplants. If possible, move transplants outside for a portion of each day. Start by placing them in a shady, protected location and gradually move them into a more exposed, sunny location as the week progresses. Hardened off cabbage, broccoli, cauliflower and onions can withstand temperatures near 20 F without being killed. Lettuce plants are not quite as tough but will be okay if exposed to temperatures in the mid 20s.  Don't hesitate to put these plants out now if extreme cold is not forecast.
Strawberry Planting    
 New strawberry plantings should be set early in the growing season so that mother plants become established while the weather is still cool. The mother plants develop a strong root system during this cool period when soil temperatures are between 65 and 80 degrees F. The most appropriate planting time is mid- to late March here in southern Kansas.  Space plants 18 to 24 inches apart. Later in the season, runners and daughter plants develop. The earlier the mother plants are set, the sooner the first daughter plant will be formed and take root. These first daughter plants will be the largest daughter plants at the end of the growing season and will bear more berries per plant the following spring.  When planting is done later, the higher temperatures stress the mother plants resulting in reduced growth, weaker mother plants and delays in daughter plant formation.  Fewer and smaller daughter plants produce less, resulting in a smaller crop.
Remove all flowers during the first year. New plants have limited energy reserves that need to go toward establishing the mother plants and making runners rather than making fruit. If fruit is allowed to develop the first year, the amount of fruit produced the second year is drastically reduced due to smaller, weaker daughter plants. Keep row width at 12 to 18 inches as strawberries bear most on the edges of the row rather than the center.  A rototiller or hoe can be used to keep the row at the recommended width.

 

Larry E. Crouse
Butler County Horticulture Agent
K-State Research & Extension
206 N Griffith, Suite A
El Dorado, KS   67042
(316)321-9660
lcrouse@ksu.edu