NDSU Crop and Pest Report

Plant Science


ISSUE 6  June 5, 2003

GROWING DEGREE DAYS AND LEAF EMERGENCE IN CEREALS REVISITED

In last week’s Crop and Pest Report, I included an article on growth staging of cereals and described how to use Growing Degree Days (GDDs) to predict leaf development of spring wheat, barley and corn. In preparing that article I used information from several different sources. Unfortunately, the GGD value I included for the development of a new leaf in barley (100 GGDs) was incorrect. It was based on a publication that used GGDs with a base temperature of 40 degrees Fahrenheit not 32 degrees (the value used by NDAWN). The correct value for barley should be 136 GGDs when using GGDs with a 32 degrees base. As noted last week the accumulations needed for leaf appearance in wheat and corn are 140 and 85, respectively. If you are interested in predicting where your crop will be in the next few weeks, I have included the long term average GGD accumulations for the four weeks of June for several locations in ND. Please refer to last week’s article if you need additional background on predicting growth stages in cereals.

Table 1. Long-term average GGD accumulations for the four weeks of June for corn (50 degree base temp.) and small grains (32 degree base temp.) for selected locations in ND (values were calculated using NDAWN data).

Location

6/1 - 6/7

6/8 - 6/14

6/15 - 6/21

6/23 - 6/28

Bismarck (corn)

85

95

108

119

Bismarck
(small grains)

210

222

233

242

Fargo  (corn)

94

106

117

127

Fargo (small grains)

220

232

242

253

Hettinger (corn)

84

96

107

116

Hettinger
(small grains)

199

210

223

235

Williston (corn)

73

84

97

109

Williston
(small grains)

217

229

242

250

 

HEAVY WINDS CAN CAUSE LEAF DAMAGE

We experienced heavy winds in parts of the state last week. Cereal crops are still small so the wind did not likely induce any lodging. However, wind and soil carried with it can be abrasive to exposed leave surfaces. If enough of the cuticle of the leaf is removed by this abrasion, bacteria can move in and damage leaf tissue. If you experienced heavy wind on your farm like we did here in Fargo, don’t be surprised if you see brown necrotic edges and tips on the leaves that were the most exposed. Many of you were out spraying herbicides either before or after the winds. Don’t confuse the damage caused by abrasion with herbicide injury. Crops will grow out of the "abrasion" injury and it will have little or no effect on yield.

Joel Ransom
NDSU Extension Agronomist - Cereal Crops
joel.ransom@ndsu.nodak.edu

 

UNEVEN SUNFLOWER SPACINGS

Poor seedbed conditions and cool soils may have resulted in uneven stands of sunflower. Last years sunflower survey pointed out that stand establishment was a major problem in sunflower production. Plants too far apart, too close together and different sizes if common in fields can result in reduced overall yield potential. Unevenness is assumed to be undesirable, but the lack of response to increased uniformity from close row spacing suggests that moderately uneven stands of sunflower may not affect yield. The effects of uniform and nonuniform plant spacings within an overall population of 20,000 plants per acres in rows 30 inches apart were studied at five locations over two years in Minnesota.

The distributions tested included uniformly spaced, clumped, and widely spaced plants: a) uniform single - plants 10.5 inches apart, b) uniform double - two plant groups 21 inches apart, c) 5-5-5 - five plants 5.25 inches apart, 31.5 - inch space, etc., d) 7-1-7 - seven plants 3.5 inches apart, 31.5 - inch space, one plant, 31.5 - inch space, seven plants 3.5 inches apart, 31.5-inch space, one plant, etc.

The uniform, single-plant spacing gave the highest average yield. Both oilseed and nonoilseed hybrids responded the same to the plant distributions.

Sunflower yields at five locations in MN.

Distribution of plants

lbs/A

Uniform single

2,455

Uniform double

2,231

5-5-5

2,231

7-1-7

2,190

LSD 5%

71

*Average 9 trials (2 years)

Plants uniformly spaced in pairs did not support each other; they lodged more and yielded less than uniformly spaced, single plants. Paired plants may give more emergence through crusted soil than single plants, but this possibility was not evaluated.

Head moisture differences among plant distributions were highly significant on the average. Plants spaced singly and uniformly had lower head moisture percentages than did the 7-1-7 arrangement in all trials.

The nonuniform plant distributions were uneven in height from preheading to maturity. The center plants of the groups of five and seven plants were 4 to 7 inches taller than the single plants. Average plant heights among the distributions did not differ noticeably.

Plant distribution did not, on the average, significantly affect test weight per bushel of seed.

 

FOXTAIL MILLETS FOR HAY

Foxtail millets are grown primarily for shortseason emergency hay crops. Several landraces have been developed over time and are grown in North Dakota. Seed of most hay millets, and other warm season forages maybe in short supply this season. Therefore anyone making the decision to plant for emergency forage should be checking with seed sources as soon as possible.

Planting of foxtail millets can be delayed until mid-June into July. When used for emergency hay production, late planting is usually encountered.

Plant into moist soil about 1 inch deep. Shallower seeding may be desirable on heavy textured soils with good moisture. Germination is fairly rapid but early seedling vigor is lacking.

Foxtail millets have low seedling vigor and in general are poor competitors with weeds. A seeding rate of 15 to 30 pounds per acre is recommended. The higher rates are recommended in eastern North Dakota with the higher rainfall potential. In western North Dakota, 15 pounds is adequate on weed free fields.

Hay Millets Include The Following:

Common Foxtail millet is fine-stemmed and leafy. Seedhead is cylindrical and compact and tapers toward the tip. The lower portion is less compact than the mid-and tip portions. Seedhead varies from 5/8 to 3/4 inch in diameter and 4 to 6 inches in length with pale yellow bristles. It is one of the earliest foxtail millets, maturing in about 70 days and producing a hay crop in about 50 days.

Siberian millet has medium-sized stems and possesses some drought tolerance. The seedhead is cylindrical, 5/8 to 3/4 inch in diameter, 4 to 6 inches long, and has purple bristles. It matures in about 75 to 80 days and produces a hay crop in 55 to 60 days. Manta, a South Dakota release, is an early Siberian millet.

Hungarian millet is characterized by a small, compact, slightly lobed seedhead which is 1/2 to 5/8 inch in diameter and 4 to 6 inches long. Bristles vary in color from clear to pale yellow through purple and black. Stems are medium in size. It is reported to do better under more favorable moisture conditions. Maturity is about 70 days and a hay crop can be ready in about 55 days.

German millet has thicker stems and broader leaves. The seedhead is distinctly lobed, measuring 1 to 1 ½ inches in diameter and 6 to 9 inches long. Bristles are greenish to purple. It is a longer season foxtail, which takes about 90 or more days to mature and 65 to 70 days to produce a hay crop. Because of its increased stem size, it takes better management than the other foxtail millets to produce good quality hay.

Harvest millets for hay in the late boot to early bloom growth stage. Any delay after full head emergence will reduce quality. Bristles become hard as maturity approaches and may cause sore mouth, lump jaw and eye infections when fed to livestock. Hay protein content is highest when the ratio of leaves to stems is high.

Curing foxtail millet requires attention as light stands tend to sun dry rapidly after cutting, while heavy stands, especially of the German type, cure at a slower rate. If expected yield levels are greater than 1 ½ tons per acre, crimping will help the curing process. Potential yield of foxtail millet hay is influenced by moisture relationships. Research trial yields from NDSU Research Centers ranged from 1.5 to 4.0 tons/acre. Data on warm season forage trials can be found on the web as follows:

Carrington NDSU Research Extension Center site:

http://www.ag.ndsu.nodak.edu/carringt/02data/forage.htm

North Central NDSU Research Ext. Center, Minot site:

http://www.ag.ndsu.nodak.edu/minot/research/02/forage02.htm

For cool season Forage trial data see:

http://www.ag.ndsu.nodak.edu/aginfo/variety/forages.htm

Duane R. Berglund
NDSU Extension Agronomist
dberglun@ndsuext.nodak.edu

 

ROLLING SOYBEAN GROUND

The objective of rolling soybean ground is to push rocks and large soil clods down to the soil surface and level the soil to allow a low combine cutter bar height during harvest. This will reduce harvest loss by cutting soybean stems below pods instead of cutting above or through low pods and leaving seeds in the field. Soybean fields are rolled after planting, either PRE or POST. Advantages with rolling before the crop has emerged are low potential for plant injury and improved seed-to-soil contact. Disadvantages are increased potential for soil-surface crusting in wet soils and soil erosion.

Rolling fields after the crop has emerged will potentially cause plant injury including crushed leaves and cracked or broken stems. Plants will die if the stem is broken below the cotyledon leaves, due to loss of all growing points. Injured plants may be more susceptible to lodging and disease. Limited university research and farmer testimony indicates that rolling between the cotyledon and first trifoliate stages of soybean may limit injury potential. Also, rolling during the warmest part of the day on less turgid plants should reduce injury.

An NDSU rolling soybean ground trial at Carrington in 2001 indicated a trend of plant population decline as rolling was delayed from PRE to the second trifoliate stage. However, seed yield was similar among the unrolled check and all rolling treatments. A similar trial is established in 2003 at Carrington to continue examining the impact of rolling timing on soybean.

 

OVERVIEW OF IRRIGATED SMALL GRAIN MANAGEMENT

Interest has recently increased in growing irrigated small grain as a rotational crop with high-value crops. This article will briefly review small grain irrigation basics and recent work by North Dakota State University.

Small grain generally can be intensively managed under irrigation similarly to dryland production. It is important to maintain high-yield potential with optimum stand establishment and crop protection strategies. Timely planting and establishing a stand of 1.5 million wheat plants/acre is important. Also, providing sufficient N throughout the growing season to match grain yield and quality (e.g. protein) goals, and use of fungicides for seed, foliage, and head protection from disease are needed strategies.

Other factors to consider with irrigated small grain include economics, variety selection, and water management. Does wheat or barley have higher economic potential compared to corn or other rotational crops?

Small grain varieties differ in response to intensive management under irrigation. Averaged over 2 years (2001-02) at the NDSU Carrington Research Extension Center, wheat varieties yielded 58.5 bu (bushels)/acre with irrigation compared to dryland yield of 44.8 bu/acre. Among a database of 27 varieties, the HRS wheat varieties with the greatest response to irrigation included Amidon, Ember, Hagar, McVey, and Mercury. During the same period, 9 barley varieties averaged 84.7 bu/acre with irrigation compared to dryland yield of 70.2 bu/acre. The barley varieties with the greatest response to irrigation included Conlon, Foster, Lacey, Morex, and Robust. Besides additional water, the irrigated trials were fertilized for a higher yield goal and foliar fungicides were used. The variety databases are available by contacting the Carrington NDSU Research Extension Center.

Water management includes providing sufficient amounts of water for the crop to minimize moisture stress. As a rule-of-thumb, wheat requires about 6 inches of water as a threshold for grain yield and each additional inch of water will provide 4 to 5 bu/acre. Water stress during the tillering stage (3- to 5-leaf) will reduce number of heads/acre and number of seeds/spike (head). Water stress during pollination will reduce the number of seeds set/spike and during seed fill the weight/seed. Average water use (inches/day) for wheat and barley is about 0.15 during tillering, 0.30 during boot to dough stage, and 0.20 to 0.27 during dough stages. NDAWN provides daily, in-season estimates of crop water use

http://ndawn.ndsu.nodak.edu/index.html  

Estimating water use and irrigation scheduling requires knowledge of crop status (e.g. growth stage and rate, rooting depth, and canopy), soil characteristics (e.g. water-holding capacity), and weather conditions.

An intensive management irrigated HRS wheat trial has been conducted at the Carrington Center since 2001 and continues in 2003. The trial factors include HRS varieties, nitrogen fertility, and three irrigation strategies. Varieties tested include Alsen, Briggs, Keene, Russ, Reeder, Dandy, and Norpro. N fertilizer is applied according to recommendations for 60, 80 or 100 bu/acre yield goal. During the first two years of the trial, wheat response to the intensive management has been limited.

References available for review on this subject include the following:

* ‘Irrigation of Small Grains’. NDSU Extension Service circular SF101.

* ’Irrigation Scheduling by the Checkbook Method’. NDSU Extension Service circular AE792.

* ’Irrigation of Cereal Crops’. Saskatchewan Water Corporation.

* ‘A Report of Agricultural Research and Extension in Central North Dakota’. 2002. NDSU Carrington Research Extension Center. Volume 43.

Greg Endres
Area Extension Specialist/Cropping Systems
Gregory.Endres@ndsu.nodak.edu

 

ALFALFA HARVEST IS UPON US

Alfalfa harvest has begun in westcentral Minnesota and just starting in eastern North Dakota. We harvested the first treatments on our research plots on May 28 and the varietal trials on June 2 and 3.

Many alfalfa fields harvested four times or three times with the third cut in September experienced some winter injury. If winter injury was severe, forage quality should be sacrificed for stand maintenance. Let alfalfa in the uninjured area reach about 25% bloom so that injured areas can regain some plant vigor prior to harvest. If winter injury was not a factor, then harvest for quality.

Maturity stage and plant height influence forage quality of alfalfa with plant height frequently affecting forage quality more than maturity stage in the first harvest. If your objective is to get prime hay in the bale, harvest must occur around 25 inches of growth in early years like this. The plant maturity stage will vary, but it could be as early as late vegetative to very early bud. Last year Vernal alfalfa harvested at 22 to 23 inches in the late bud growth stage had 27% ADF and 38% NDF in grab samples. Allowing for harvesting losses, this was the correct stage to harvest in 2002 (a cool, late spring), but the correct maturity stage this year is earlier, very early bud.

Harvest of irrigated alfalfa should occur now in eastern North Dakota and be starting in central and western areas if your attempting to get prime hay in the bale. But, base your decision to harvest on the height of the plant (not calendar date or maturity stage). If the alfalfa is approaching 25 inches, harvest if the weather allows.

 

SPRING BLACKSTEM IN ALFALFA

Several reports from the western North Dakota concerning disease in alfalfa have occurred this past week. It appears spring blackstem is very active. The causal organism of spring blackstem is the fungus Phoma medicaginis Malbr. & Roum. var. medicaninis Fckl. The general symptoms are numerous small black to dark brown spots developing on the lower leaves, petioles, and stems. These leaf spots can be confused with common leafspot caused by Pseudopeziza medicanginis (Lib.) Sacc., but common leafspot does not have spots on the stem.

As the disease progresses, the spots coalesce and blacken the stem and leaves. If severe early in the spring, the young stem can be girdled and killed, which has occurred on at least one irrigated field in the Bismarck area. Generally the disease is active later in the growth of alfalfa so it doesn’t kill the stem, just discolors the stem and caused earlier leaf drop and greater leaf loss in harvest. Feeding hay with spring blackstem is not known to cause significant health problems in livestock.

Spring blackstem occurs in cool wet periods so it is most commonly found in the spring and fall. The fungus fruits readily on overwintered stem lesions, producing brown to black pycnidia. When pycnidia are placed in water, the spores escape in gelatinous ropy or wedge-shaped masses. Spores are spread primarily by water, but may also be spread by wind and insects. In early spring, new shoots are infected as they grow through the crop residue or stubble. Dew or rain is necessary for pycnidia to release spores and for infection so wet conditions are a must for infection.

Highly resistance varieties are not available for spring blackstem, but some moderate resistance does occur. Control measures recommended for spring blackstem include the following: 1) early cutting to reduce leaf loss, 2) use certified seed produced in arid areas and consider seed treatment, and 3) foliar fungicides effectively reduce disease severity and may benefit seed crops but are unlikely to be economical on hay crops due to repeated applications required and most fungicides are not cleared for application to hay. Practically then, only early harvest is the only management practice available once the seed has been planted.

Dwain W. Meyer
Extension Specialist, Forages
dmeyer@ndsuext.nodak.edu

 


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