ISSUE 2 May 14, 1998
SOLID SEEDING CONFECTION SUNFLOWER
Research results of NDSU oilseed sunflower trials have shown no significant yield differences between solid seeding and conventional row spacings (30"). In fact most NDSU research studies indicate higher yields of 5 to 25% with narrow rows compared to conventional row spacings. Higher yields were achieved with even stand establishment and good weed control. Also there havent been any differences in other agronomic traits such as oil content, plant height, dry down, or test weight being reported.
What about confection sunflower? The most important concern for confection sunflower besides the yield is the impact of narrow rows on seed quality. Research has been conducted on row spacing with confection sunflower the past two growing seasons at the NDSU North Central Research Center.
Confection sunflower at 18,000 plants per acre at 4 row spacings, North Central Research Extension Center, Minot, ND 1996-97.
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Over the past two years there havent been any significant differences between row spacings with head diameter, seed size, test weight, and yield. There is a trend that as row spacings narrow from 30 inches lodging increases. Plant population for confection sunflower in narrow rows should be similar to conventional row spacings, approximately 18,000 plants per acre. A good weed control program is essential. The most important consideration is even stand establishment which leads to proper drill calibrations. Calibration to minimize skips and doubles is very important. Keep in mind that the distance between seeds increases within the row as the row spacing decreases. An example would be a producer that conventionally seeds confections at 18,000 plants per acre in a 30-inch row would calibrate for an optimum distance of 10.5 inches between seeds in a row. Solid seeding a 7.5 inch spacing at 18,000 plants/acre would result in an optimum distance of 42 inches between seeds in a row.
Area Extension Agronomist
SEED CANOLA NOW BEFORE ITS TOO LATE!!
As we get later into the planting season, its suggested that canola (a heat sensitive crop) be seeded first and then complete small grains, sunflower and beans planting later. Research has shown that canola yields drop quickly if planted late.
For canola planted acreage south of U.S. Highway 2, its suggested canola always be planted before small grains and, if possible, before May 15. For the NE and areas and growing areas north of Highway 2, canola should be planted no later than May 25.
The optimum planting date for canola is late April-mid May. Canola yields have decreased sharply across most of the state (except the northeast) when canola is planted beyond mid-May.
Canola is more sensitive to heat stress than all small grains, flax, and other cool season broadleaf crops, thus the importance to seed canola early. Canola is also quite tolerant to spring frosts.
Once weather conditions are favorable to seed, and if seeding canola this year, seed canola first prior to small grains to avoid the potential of decreased yields due to late seeding.
RELATIVE MATURITY OF VARIOUSFIELD CROPS
Since the 1998 planting season is off to a good start, being 10-14 days ahead of the past five years, readers may wish to note the approximate crop maturity differences. Below is a listing of the average days to physiological maturity of many crops grown in North Dakota. Early Killing frosts, plus extreme high temperatures at flowering time are the most limiting factors of high yields.
Seeding to Physiological Maturity
NDSU Extension Agronomist
CRUSTING, CROP INJURY AND REPLANTING DECISIONS
Concerns over dry seed beds a week ago have been alleviated by recent heavy rains, but seed planted in those dry seed beds may now face crusting problems. Crusting will be most noticeable is in areas with low organic matter and little surface residue, and especially in fields were excessive tillage was done.
Crusting sufficient to prevent the coleoptile of a germinating small grain to penetrate the soil surface can result in severe stand loss. When the crust is not broken the first leaf of the seedling will break through the coleoptile and grow under the crust. Once this has happened seed nutrient stores are quickly depleted, since the seedlings are not photosynthetically active, resulting in plant death. Consequently, managing a crusting problem is a critical time issue especially during warm weather.
Soil crusting can be alleviated in any number of ways as long as it does not disturb the sub soil. Light rain is idea but when this is not in the forecast, a light harrow, double disc drill set very shallow, or rotary hoe are examples of equipment that can effectively be used. The objective is to very gently break the soil crust.
Invariably there are going to be areas with less than desirable crop stands due to crusting or a host of other causes such as frost, insect and disease injury which brings up the question of replanting. The decision to replant requires careful assessment of crop injury, alternate crop choices and cultural practices related to crop growth and development. Each case of injury should be considered individually. The following information is meant to aid in the process of determining the extent and severity of injury prior to making the decision to replant.
Crop injury must be determined and potential crop yield estimated to determine if a crop should be replanted. Any reduction in stand can reduce yield while leaf loss during early crop development has a smaller effect on yield; however, as the crop matures it is unable to produce new leaves and then leaf loss is more damaging to yield. Small grains have a large capacity to compensate for stand reduction through tillering and increased head size. Leaf damage on young plants will be replaced but once the plant has reached the jointing stage its ability to produce new leaves and tillers is lost.
During early development the growing point of small grains is below the soil surface making it less susceptible to injury, as the growing point moves above the soil surface it becomes more vulnerable. In this early state, plants can suffer complete loss of above ground vegetation without plant death occurring. When hail, frost or similar types of injury cause severe foliar damage, waiting several days after the injury occurs may be required to make an accurate determination of stand reduction. The growing point is a good indicator of plant health. The growing point should be white or cream colored. Darkening or softening of the growing point usually precedes plant death.
Seeding rate trials in North Dakota indicate that optimum plant populations for maximum yield in both barley and wheat is about 30 plants per square foot. Any reduction in the plant population will reduce yield but the reduction in yield is not proportional to the reduction in plant population. A 60% reduction in a plant population may only result in a yield loss of 20% under good growing conditions. Good yields have been obtained with plant populations well below 10 plants per square foot. Replanting small grains should not be considered when populations are at 10 plants per square foot or greater.
Probably more important than plant population is planting date and its effect on yield. In North Dakota delays in planting small grains past May 15 typically result in yield reductions on the order of 1.5 to 0.5 % per day of the total yield. While it is difficult to make yield comparisons between an early planted crop with a less than desirable stand and a much later planted crop with an optimum stand, it is safe to say when the original crop is planted well before mid May its yield potential may be better than that of a replant. The availability of soil moisture must be considered, as it may be depleted by the current crop and will be further reduced during replanting.
Comparison of the estimated yield of the injured crop with expected yield of a replanted crop plus replanting costs most often indicate crop stands should be left. If after careful evaluation of a damaged crop it is determined that replanting will be done, here are a few things to consider. Depending on how late it is in the season it may be desirable to switch to a crop that can be planted very late such as millet, dry beans, and buck wheat. Previously applied herbicides should be evaluated for their potential to damage a crop.
The final decision on replanting should be an economic one, based on sound agronomic information. If the cost of replanting is equal or greater than any yield gains, then exercise is the only thing gained. The critical determination is the yield potential of the damaged crop compared to that of a replant, and the cost of replanting.
Michael D. Peel
Extension Small Grains Agronomist
MANAGING DRIFT IN 1998
Off target drift of pesticides is always a serious concern for applicators, regulators, and the damaged party. However, 1998 will be an especially sensitive year for drift in North Dakota because of the radical acreage shift from small grains to other crops, particularly broadleaf crops. This year canola acres will soar to near 1,000,000, sugarbeets will set new records in the valley, soybeans are expanding out of the SE corner of the state, spuds are moving to the irrigated areas west of the valley, and pulse crops are setting new acreage records as well. All this means greater potential for herbicide injury to these crops, particularly from broadleaf herbicides which are traditionally used on wheat and barley.
Fortunately, we have the technology to virtually eliminate drift. The National Spray Drift Task Force spent over $17 million and took over five years to study the issue. The results; confirmation that given the proper use of existing technology and sound applicator decision making, drift can be reduced to a negligible level. The task force identified eight ways to reduce drift. They are:
Andrew A. Thostenson
NDSU Pesticide Program Specialist
TOO MUCH WATER?
Timely rainfall is a blessing in agricultural and horticultural cropping systems. Many homeowners were delighted with the fact that their preemergence "Weed & Feed" applications were completed before the rains came. Even the early gardeners - those who dared to set out their plants - before the last average frost date - are delighted to be getting a jump on the season for a change, along with a boost from Mother Natures reservoir!
In spite of the heady feeling that we may get past the "frost date" this year without any dire consequences, it bothers me that I see automatic irrigation systems cycling on during these rainy days. I have had a couple of calls from individuals saying their "irrigation man" came out and set the controller for them to come on every other day (EOD). Without a rain gauge or moisture sensor hooked up to the controller, the system is "dumb" as to what the weather is doing, and comes on in spite of the fact that over 2 inches of rain have fallen since Friday. However, the homeowners are not dumb, and should exercise their intelligence to shut their systems off during any rainy period.
Home irrigation systems are set up to deliver water 2 basic ways; through stationary "pop-up" heads, and rotary gear-driven or impact heads for larger areas. Running the stationary heads for just 1 hour will deliver 1 inch of water, while running the rotary heads for 1 hour will deliver about 0.3 to 0.4 inch of water. This terminology often fails to communicate just how much water this is to the average user. For every 1000 square feet of turf or other area irrigated in this fashion, figure about 624 gallons for each inch of water. Thats almost 5,000 gallons of water for the average lawn of 8,000 square feet. Multiply that by the number of weeks in an average growing season in ND, and the amount tallies to over 107,000 gallons of water - just for one residential area! Too much water!
When a soil is kept in this almost perpetually saturated state, the root system fails to develop properly due to a lack of oxygen in the soil pore space. Grass, and other plant material subjected to this high soil water content will become vulnerable to a host of diseases and stresses, limiting their longevity and usefulness in the landscape. Except in the worst weather conditions and sandiest soil, irrigating more than a couple of times per week tends to waste water. An EOD regime will provide more water than is needed for healthy plant growth in most instances.
If the homeowner lacks sufficient information on how to reprogram their irrigation controllers, call a local installer and have them provide instruction. This will save money on wasted water and result in healthier plants as well. Properly designed, installed, and managed automatic irrigation systems can save water and money. While the design and installation is usually the contractors responsibility, the management of it often falls on the shoulders of the homeowner. Encourage water conservation through good management of the excellent technology the irrigation industry has developed.
Ronald C. Smith, Ph.D.
NDSU Extension Horticulturist and Turfgrass Specialist