April 7, 2003

by Kevin Black, FS System insecticide/fungicide technical specialist and trial coordinator
Growmark / FS System

How do You Pick the Ideal Planting Date?

After harvest, determine which planting date yielded the most.If that is not an option, using  local historical information and environmental conditions should help with the decision process.There is little data available to fine-tune the best week.Soil temperature and moisture relationships are in control
of stand establishment and early growth, and we have no control over either.

The best way to decide when to start planting is to watch soil conditions and forecasted air
temperatures.If the soil temperature is at least 55O F at a 4-inch depth by 1 p.m.
and the weather forecast is for temperatures at or above 55O F, planting may be an option to  consider.Keep in mind that the chance for development of a poor growing environment and possible
loss of stand increases with early planting dates.Consider historical information when making the planting  date decision.A running history of success, the latter part of April or early May, suggests that early April  may not be worth the risk.

Prepare Your Service Call Tool Box Now

Pull the shovel or spade out of storage and make sure it represents your level of professionalism.Find the magnifying lens and put it in a place that will be easy to find.Find the tool you use when digging up the corn and soybean seeds prior to emergence.Have a 25-foot retractable tape measure available to help with stand counts.Throw-in some zip-loc plastic bags (2 gallon) for plant samples that you may send to the university for evaluation.Have a soil probe and sample bags available if a soil test is needed to help diagnose a problem.Consider adding a water source to your tool box along with soap and towels to wash up after digging in pesticide-laced soil.Have a supply of Service Call Report Forms or Replant Decision Forms conveniently available.Think of what you expect from the professionals you work with and expect nothing less of the way you approach your customers.

Conserving Soil Moisture in a Dry Spring

Some areas are experiencing drought conditions.Even though we know that this moisture deficit can be made up with just a few key rain events, we also know, from experience, that timely rainfall is THE most critical factor in producing a good crop. With this in mind, what practices can help hedge against the potential for a dry growing season?Following are a handful of proven practices that can help. Avoid soil compaction.(Is this trip necessary?)The effects of soil compaction are magnified in dry weather.
Conserve soil moisture by reducing the number of tillage trips.Consider a reduced tillage approach, or even no-till.
Reduce the amount of time between seedbed preparation and planting.Stirring the soil surface allows
moisture to leave.The planter pass helps compress the soil around the seed and conserve moisture.
Boost soil fertility.Abundant plant food reserves help offset dry weather stress.Consider a band
application of fertilizer at planting.
Diversify your seed portfolio.Select crop varieties with proven local performance, but make sure that
there is a mix of adapted maturities and agronomic features.(Tip:Plant early varieties first.Plant later-maturing varieties after the early ones.This is especially important for corn hybrids.)
Spread your planting dates.Plant first on those well-drained, early-warming soils.Go later on the cooler soils.Be selective.Avoid the temptation to run hard and get the entire crop planted in just a few days.
Control pests.Weeds, insects and plant diseases all add to the crop stress.Knowledge of the field history, plus timely scouting, allows you to select pest control strategies specifically tuned to the individual field.
Don't delay too long in controlling weeds.A good deal of research has proven that some weeds need to
be controlled early to avoid undue competition with the crop.

Remember to Check Stored Grain

As we go through this transition from winter to summer weather, farm-stored grain should be inspected at least once a week.Because of the condition of much of our corn crop as it went into the bin last fall, regular inspection of the grain is especially important this spring.Warmer air temperatures and higher humidity can create problems for farm-stored grain.Grain that was chilled during the fall and winter months can now condense moisture.Natural convection flow of air provides the vehicle for getting the warm, moist, outside air in contact with the cool grain.

Inspect fans to make sure that they are still completely sealed, except during use.This will help
limit convection flow of air within the bin.Check the grain surface at the top of the bin for evidence of
mold, crusting, or insect activity.(Remember not to enter a bin without a buddy on the outside and don't walk on crusted grain without first probing to be sure that there is no space underneath.)Be alert for musty odors that can signal spoilage.Schedule use of fans to gradually warm the grain to within 10ºF of  the average monthly temperature.(Grain generally does not need to be warmed much above 60ºF unless your management plan calls for higher temperatures.)

If the grain is to be stored into the summer months, consider using insect traps to help monitor insect
activity in the bin.Barrier insecticide treatments to the grain surface can help prevent insects from
entering at this point.Your elevator may be willing to loan a manual probe to you periodically so that you can check for insects in the grain mass.Above all, don't let problems get started.It is much easier
to prevent problems than it is to correct them.

Wheat Spring Growth

Since most wheat that has the ability to green up has done so by now, our present concern is in
evaluation of poor stands and trying to explain the various causes of poor stands to the grower.

Winter wheat prepares for winter cold temperatures by undergoing a fall "vernalization" period, typically
a few days where temperatures drop consistently below 50°F.Sugars accumulate in the wheat crown area, helping the plant tissue to resist damage from freezing.If winter temperatures fluctuate between warm and cold, the young wheat plant may use up its sugar reserves and then suffer from freeze injury.Some wheat varieties, many which are high-yielding, "break dormancy" with only a little exposure to warm temperatures.This may also result in increased freeze injury.

Experience has shown plants that have reached the 3-leaf growth stage with 2 or more tillers (Feekes
stage 2.5) will most successfully overwinter.Too much fall growth can be detrimental since leaf diseases, such as Septoria, benefit from the additional foliage, and the plants also move too much sugar into the leaves instead of accumulating it in the crown where it can help reduce freeze injury.Too much fall growth from early planting is also an invitation to Hessian fly and disease problems.

In the spring, following tiller formation, wheat stems begin to elongate and stem nodes can soon be felt
or observed by dissecting the plants.This period of growth is often referred to as "jointing."Growth during this period is rapid, and the growing point with the embryonic head is quickly pushed above the ground.Frost or freeze during this rapid growth phase can seriously reduce yields. About two above-ground nodes are formed in the typical wheat variety before vegetative growth slows with emergence of the flag leaf (Feekes stage 8-9).Application of Tilt fungicide is permitted through Feekes stage 8, where the leaf collar of the flag leaf is fully visible.

[Management Note:When spring growth of above-ground tissue begins, there should be a corresponding growth of new roots.Spring growth essentially precedes both up and down in healthy
wheat plants.This is easily observed by digging young plants and washing off the root system.]

When the flag leaf is fully emerged, the developing head begins to swell within the leaf sheath of the flag leaf.This is Feekes stage 10 and is also called the "boot" stage.Three stem nodes are detectable
on the typical wheat variety and, during this time, growth fully shifts into reproductive mode.Heavy leaf
disease development or insect injury at this time of growth can severely reduce yields.

A diagram of the Feekes wheat development stage system is included here.Refer to this chart for
additional growth staging information.

Time to Watch for Wheat Viruses

A number of virus diseases infect wheat.Four of the most common virus diseases in the Midwest
include: Wheat Soil Borne Mosaic, Wheat Spindle Streak Mosaic, Wheat Streak Mosaic, and Barley Yellow Dwarf.Both fall and spring infections occur with these diseases, although it is the fall infections that typically result in the greatest yield losses.

Wheat Soil Borne Mosaic (WSBM) and Wheat Spindle Streak Mosaic (WSSM) viruses are soil
borne, and often vectored (carried from the infection source to the wheat plant) by the fungus, Polymyxa graminis. Wheat Streak Mosaic (WSM) is vectored by the wheat curl mite, and Barley Yellow Dwarf (BYD) is vectored by several aphid species.

Because of the means of infection, WSBM usually has a greater impact with early fall planting when soil conditions are slightly moist.This favors activity of the fungus vector.Likewise, WSSM infection is
favored by early wheat planting followed by conditions of adequate-to-surplus soil moisture.Spring
infection occurs, but usually with much less impact on yield than with fall infection.

These two viruses have a temperature threshold that also affects their activity.Leaf symptoms and
corresponding activity of the viruses disappear when temperatures rise above about 68°F.Sunshine also enhances the reduction in virus activity.Finally, WSBM often appears in lower, poorly drained areas, while WSSM tends to be more widespread in fields.Since soil temperature influences activity of the fungus, Polymyxa graminis, planting after the "fly-free-date" is a good management practice.Some varieties have resistance to these viruses but this resistance has been poorly documented.

Wheat Streak Mosaic Virus infection is favored by early planting because of the activity of the vector,
the wheat curl mite.The wheat curl mite has several hosts besides wheat, so control of the vector for
management of WSM is impractical.Destruction of volunteer wheat, however, has benefits for elimination of a disease reservoir, as well as elimination of one source of the wheat curl mites.Planting
after the "fly-free date" is usually a sound management practice.

Barley Yellow Dwarf Virus is favored by early planting, since this favors buildup of the aphid vectors.
For this reason, destruction of volunteer wheat helps to eliminate the reservoir for this disease, and
planting after the "fly-free date" helps to avoid activity of the aphid vectors.Some varieties seem to be
less affected by BYD than others.

Stay alert for altered weed emergence patterns, erratic emergence

The cooler than normal weather last fall, followed by the delay in soil warm up this spring, has caused some interesting shifts in greenup of winter annual weeds, and may cause some erratic emergence pattern.Dr. Jerry Doll, University of Wisconsin, indicates that some winter annuals, particularly chickweed, have completely lost all top growth and may not continue to grow.Dandelions and other perennials and biennials have little top growth to date and will be a later than normal control challenge.Ron Hines, Dixon Springs Ag Center insouthern Illinois, indicates the progression of greenup is fully two weeks behind that of 2002.

Before we get too comfortable with a later scenario, I should note that Dr. Christy Sprague at the University of Illinois indicated giant ragweed emergence had occurred at Champaign as of the third week of March.

Our best management practice suggestion is to scout the field before making a burndown application to assure you have the correct mix for the weeds and weed development in the field.

For localized information, contact your nearest FS member cooperative.