Proper Timing for Crabgrass Preventers
Crabgrass preventers are another name for preemergence herbicides
that prevent crabgrass seeds from developing into mature plants. Many
people have a somewhat foggy idea of how they work and assume they kill
the weed seed. Such is not the case. They do not kill the seed or even
keep the seed from germinating but rather kill the young plant after it
germinates. Therefore, they do not prevent germination but prevent
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. Microorganisms and natural processes
begin to gradually break them down soon after they are applied. If some
products are applied too early, they may have lost much of their
strength by the time they are needed. Most crabgrass preventers are
fairly ineffective after about 60 days, but there is considerable
variation among products. (Dimension and Barricade last longer. See below.)
For most of Kansas, crabgrass typically begins to germinate around
May 1 or a little later. April 15 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. 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 is not 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 may be difficult to find products that contain preemergents
without fertilizer. Those that don’t contain fertilizer are listed
below. I didn’t find any products containing Barricade that did not also
have a fertilizer. If anyone knows of other products that should be
listed, let us know and we will publish them in a later newsletter.
– Scotts Halts
– Howard Johnson Crabgrass Control Plus with 0.37 Prodiamine 00-00-07
Team (Benefin + Trifluralin)
– Hi-Yield Crabgrass Control
– Hi-Yield Turf & Ornamental Weed and Grass Stopper
– Bonide Crabgrass & Weed Preventer
– Green Light Crabgrass Preventer
Apple Tree Sprays
Apples are the fruit most likely to be damaged by diseases and
insects of any fruit grown in Kansas. Two common diseases on apple
trees are cedar apple rust and apple scab. Though some apple varieties
are resistant to these diseases — including Liberty, Jonafree, Redfree,
Freedom and Williams Pride — most varieties are susceptible. For a
listing of the disease resistance of various cultivars, go to:
Fungicide sprays during April and May are critical to preventing
disease on susceptible varieties. The first spray should go down when
leaves appear. A fungicide that is available to homeowners and very
effective for control of apple scab and cedar apple rust is myclobutanil
(Immunox and F-Stop Lawn & Garden Fungicide). There are several
formulations of Immunox but only one is labeled for fruit. Check the
label. Sprays should be done on a 7- to 10-day schedule to keep the
protective chemical cover on the rapidly developing leaves and fruit.
These diseases are usually only a problem during April and May.
An insecticide will need to be added to this mixture after petal
drop to prevent damage from codling moths that cause wormy apples. We
have five products that can be used. They are listed below along with
the maximum number of sprays that can be used per year.
Product Maximum Number of Sprays/Year
Bonide Malathion 2
Bonide Fruit Tree Spray 2
Bonide Fruit Tree and Plant Guard 4
Ortho Flower, Fruit, & Vegetable Insect Killer 4
Cyd-X No limit
In order to protect bees, DO NOT use any insecticide during bloom.
Wait until petal fall.
Although gardeners may continue to use myclobutanil after May,
certain other fungicides are more effective on summer diseases such as
sooty blotch and fly speck. Consider using Bonide Fruit Tree and Plant
Guard or Bonide Fruit Tree Spray after petal drop as both contain an
insecticide(s) and fungicide(s). However, you are limited in the number
of applications per year allowed.
An organic control with the trade name Cyd-X is also labeled but
will control only codling moth.
A spreader-sticker can be added to the fungicide-insecticide
chemical mixture to improve the distribution and retention of the pest
control chemicals over the leaves and fruit. Sprays are applied every 10
to 14 days. A hard, driving rain of about 1 inch or more will likely
wash chemicals from the leaves and fruit. In such cases, another
application should be made.
Another organic control that is often overlooked is bagging. There
are bags made specifically for this purpose and are called Japanese
apple bags. However, 3 lb paper bags (lunch bags) can work as well.
Cut the lunch bags down to six inches long and cut a slit to slip over
the stem of the apple. Place the bag over a single fruit when it is the
size of quarter (about 3 weeks after petal fall) and secure with a twist
tie. The bag should be removed three weeks before harvest to allow the
apples to color. The Japanese apple bags already have the slit cut and a
twist tie built in. Once the bags are placed on the fruit, no
additional sprays are needed. The bags prevent both fungus diseases and
attacks by insects. For a video illustrating all the steps required for
bagging apples, see https://www.youtube.com/watch?v=sbbmgJ5F1wc .
Following are the steps that need to be taken if bags are not used and
the trees will be sprayed.
Leaves Appear: Immunox or F-Stop Lawn & Garden Fungicide
Petal Drop: Add insecticide to the Immunox or F-Stop. The mixture
is Immunox or F-Stop + one of the listed insecticides.
June 1: Drop the Immunox or F-Stop so you are applying only Bonide
Fruit Tree and Plant Guard or Bonide Tree Fruit spray. Another option is
to use one of the other listed insecticides plus Captan.
Spray every 10 to 14 days or until the fruit is bagged. (Ward Upham)
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 in southern Kansas and
late March to mid-April in the northern areas of the state. 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 fewer berries,
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. (Ward Upham)
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. (Ward Upham)
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. (Ward Upham)
Growing Large Onions
Onion types: Onions bulb in response to daylength and are
classified as short-day, intermediate-day and long-day plants. Onions
classified as short-day are triggered to bulb earlier than
intermediate-day plants and intermediate-day plants are triggered to
bulb earlier than long-day varieties. Intermediate-day onions are best
adapted to Kansas conditions if you are looking for large onions. We
can also grow short-day varieties but bulbs will be smaller than if they
were grown further south because the plants are still small when they
are triggered to bulb.
Varieties: If you wish to grow large onions, choose an intermediate
type such as Candy, Red Candy Apple or Super Star.
Sets or plants: Though onions can be grown from seed if started
inside, we are too late to raise seed-grown plants this year.
Therefore, we must grow them from sets or plants. Sets look like
miniature, mature onions and are most often unnamed. They will produce
small mature onions. Therefore, don’t use sets if the goal is large
onions but rather plants of one of the three varieties mentioned above
or of another intermediate-day type. However, sets are fine if you want
to grow green onions (scallions) or don’t care about the size of mature
onions. Any sets that are larger than a nickel in diameter will likely
go to seed and should be used as scallions. Those that are smaller than
a nickel should produce mature bulbs.
Fertilizing: Onions have shallow root systems and need good, even
moisture and adequate fertilizer to develop large bulbs. Fertilize
according to soil test and work the fertilizer into the soil before
planting. If a soil test hasn’t been done, use a complete, balanced
fertilizer such as a 10-10-10 at the rate of 1 pound per 100 square
feet. Actually, any fertilizer with the three numbers being similar
will work; just follow the directions on the bag to determine how much
Onions respond well to sidedressing (fertilizing as the plants are
growing) about 3 weeks after the plants have started to grow. Use a
fertilizer composed primarily of nitrogen such as nitrate of soda
(16-0-0). This fertilizer may be applied at the rate of 2 pounds (about
4 cups) per 100 feet of row. High nitrogen lawn fertilizers such as a
27-3-3, 30-3-4, 29-5-4 or something similar are also good choices, but
the rate should be 1 pound (2 cups) per 100 feet of row. Do not use lawn
fertilizers that contain weed killers or weed preventers.
Planting: Space plants 4 inches apart to provide adequate room for
bulb expansion. Set plants 1 to 1.5 inches deep. Rows can be spaced 12
to 16 inches apart or whatever is convenient.
Care: Keep the onions weeded to reduce competition. Water once per
week if no rain. Onions should be ready for harvest the first half of
July or earlier. (Ward Upham)
Breaking the Pine Wilt Cycle
Pines have several disease and insect problems. One of them is
pine wilt disease. It kills the entire tree quickly.
Pine wilt is caused by the pinewood nematode, a microscopic worm.
The nematode is spread by the pine sawyer beetle. The nematode feeds and
multiplies in the tree’s resin canals, causing wilting and death in
several weeks to several months. The nematode and beetles spend the
winter in the infected tree. In spring, the beetles emerge starting
around May 1, carrying nematodes to new trees and continuing the cycle
The disease is common in the eastern half of the state, and it is
spreading west around 10 miles per year. There have been pockets of
infection in the western part of the state.
In Kansas, new pine wilt infections are most visible from August to
December. Trees wilt and die in a short period of time, from several
weeks to a few months. In the first stages, the needles turn grey or
green, then yellow and brown. The discoloration sometimes occurs branch
by branch, sometimes all at once. With pine wilt, eventually the whole
tree dies, within a few
months. The brown needles stay on the tree for up to a year after the
tree has died. Another key
symptom is reduced resin. On a healthy tree, sticky resin bleeds from
the site of a wound. In
contrast, if a tree has pine wilt, the resin is often reduced or absent,
and branches become dry or
There is a website with color photos and descriptions at the
There are images to compare and contrast pine wilt with other pine
With the other diseases (tip blight, needle blight) only parts of
the tree turn brown. With pine wilt, the whole tree is brown and dead.
If you aren’t sure if your tree has pine wilt or something else,
contact your local K-State
Research and Extension Office or the K-State Diagnostic Lab
If a tree has pine wilt, the tree should be cut down by April 1 to
make sure there is time to
destroy the wood by May 1, when the beetles start to some out. Cut the
tree to the ground—don’t
leave a stump. Chip or burn the wood immediately to destroy the beetles
and nematodes. Don’t
keep pine wood around for firewood. (Megan Kennelly)
Many gardeners assume that compost is acidic but such is usually
not the case. Compost is more often alkaline than acidic. The possible
use of alkaline composts on highbush blueberries was enough of a problem
that Oregon State University carried out a study that included
determining the pH of various composts. The listing below is of some of
the composts Oregon State University studied and the pH of those
materials. We have not listed those composted from materials not common
in Kansas such as hops and mint hay.
Mixed Manure 7.9
Horse Manure 6.4
Dairy Solids 8.0
Yard Debris 7.7
Composted Bark 5.4
It is interesting to note the tremendous variability in pH; from
8.0 for dairy solids to 5.4 for composted bark. Therefore, it is
important to perform a soil test on soils that have been heavily amended
with compost as the compost may have affected the pH. (Ward Upham)
Contriubtors: Megan Kennelly, Plant Pathologist, Ward Upham, Extension
Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
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