ISSUE 2    May 12, 2005

FLAX PLANTING RESPONSES

Seeding of flax is suggested at a lower rate of 20-35 lbs/A in the west and 35-45 lbs/A in the northern and eastern high rainfall areas. Flax seedling stands my sometimes be poor due to dry soils, deep seeding, soil crusting, herbicide injury or other factors. Results below show that good yields can result from lower seeding rates and also result in less lodging in lodge prone environments.

Planting Rate

Environments

Lodging

 

Non-Lodged

Lodged

 

lbs/a

-----Yield (bu/a)-----

0 to 9

20

23.1

27.2

1.6

30

25.1

27.5

1.9

40

25.6

23.6

4.8

50

26.7

25.0

4.47

660

27.1

23.0

4.3

LSD 5%

1.2

NS

2.4

3 years. - Langdon, Cavalier and Tolna, ND. Lodging Scores: 0=no lodging 9=Flat.

How late can flax be planted and still get fairly good yields?
Below are research results from flax seeding date studies conducted over 9 years at the North Central Research Extension Center at Minot, ND.

Flax Seeding - Minot, ND

Seeding Period

Average* Yield bu/A

% Early seeded date

1st (Early-May)

24

100

2nd (Mid-May)

22

93

3rd (Late-May)

18

79

4th (Early-June)

16

68

5th (Mid-June)

11

48

6th (Late-June)

4

16

Early June planted flax was 8 bu/A less than early May planted flax. These data suggest that all flax should be planted between late April to May 15 to ensure maximum yield potential. Good seedbed preparation, adequate shallow seed placement to moisture, weed control and fertility management also will contribute to high flax yields. Yield goals of 30+ bu/A are not unrealistic for well managed flax production.

 

PLANTING SOYBEANS ON SOYBEANS

Knowledge, ease and Roundup Ready Soybeans have many farmers considering planting two, three or more years of soybeans in the same fields. This may appear to be a good option after the initial pencil pushing but should be examined more closely. This may look good in the short run, but over a longer period could result in a disaster. Although production costs may be lower, there is a good chance that yields may be lower as well and the grower not even note the potential yields they have lost. Additionally, producers may be setting themselves up for long term management headaches. The two major concerns with planting soybeans on soybeans are: disease problems and weed specie shifts.

First what about yield potential?

It is not a certainty that a second year of soybeans will yield poorly, although this behavior does tempt fate. Organisms that attack soybeans are a major concern. Problems that immediately come to mind are certain root rots, white mold, brown stem rot and soybean cyst nematode (SCN which has now been identified and reported in southeastern ND.). SCN have been well documented to be greater problems in continuous soybean and we already have enough problems to go around. White mold, certain root rots and SCN persist in the soil. Brown stem rot overwinters and can also live as saphrophyte on soybean residue. A few other organisms that survive the winter on residue include those causing bacterial blight, stem canker, pod and stem blight, brown spot, etc. Soybeans on soybeans benefit these organisms as follows: the first year of soybeans allows reproduction and buildup of disease inoculum and nematode populations. The third or fourth year of soybeans planted into the elevated disease or nematode levels can bring about drastic results and low yields if conditions are right for disease buildup.

If we have a dry 2005 summer and somewhat droughty conditions, disease incidence could be down. If we have a wet summer, then disease problems could be higher.

The higher the pathogen levels, however, the greater the potential for yield loss. A piece of good news is that some root rot causing pathogens (Phytophthora, Fusarium, Pythium, and others) are already prevalent in the soil and a few more probably won't make a major difference. Also there are a number of cultivars of soybean which are resistant or tolerant to Phytophthora root rot. It mainly depends on the race and if you have the correct resistant gene in your variety.

Weed species shifts, or the increase of a particular weed species in the population of a field because it escapes by herbicide tolerance or time of emergence, have been known to occur. The increase of certain nightshades, biennial wormwood, ALS resistant Kochia and waterhemp are examples. By planting the second or third year of soybeans and applying the same herbicide or cultural practices you are helping speed the selection process along. From a natural ecological perspective your field wants to have weeds growing in it. The objective is to prevent a buildup of those weeds that are hard to control.

Some suggestions if you have no other choice - Maximize the disease defensive characteristics in the varieties planted. Varieties with lower susceptibility to white mold should be selected. Go to wide rows (30 inches) as this planting pattern is less susceptible to white mold problems. Planting shorter season varieties and delayed planting may in some years help reduce white mold pressure.

Try to use a different weed control program in 2005 than in 2004 if certain weeds are starting to become a major problem. Rotate chemical families/modes of action of herbicides.

Condition and test any saved seed if that is what you will be planting. A seed treatment may be appropriate, depending on the disease, if you suspect that the seed may be infected. Remember that Roundup Ready soybean cannot be saved seed and replanted. Its against the law!!

Moldboard plowing may help control some (but not all) of the fungi and bacteria that survive on residue. Unfortunately, heavy tillage of soybean residue has other negative impacts and spring moldboard plowing is not advisable. Soil tilth can be destroyed and this increases erosion potential.

Reduce or eliminate any nitrogen application, and no need to inoculate seed unless you had poor nodule formation in last years crop. Phosphorous fertilization maybe required depending on soil tests and crop yield removed last year.

Duane R. Berglund
NDSU Extension Agronomist
duane.berglund@ndsu.edu

 

ZINC DEFICIENCY IN ALFALFA??

There is concern that there maybe significant zinc deficiency in alfalfa. Yet, I must say we have no documented response from zinc fertilization to date, only soil test results that indicates less than 1 ppm, a level normally considered sufficient. Alfalfa is not considered especially sensitive to zinc deficiency however.

Robert Nudell, my project technician, also farms and is a cash hay producer at Buffalo, ND. He reported to me late last year that his alfalfa wasnít growing well in the third harvest. He also commented that alfalfa over a buried pipeline that had been installed about 15 years ago was growing with no problems. Soil samples from over the pipeline and from the poor growth area indicated zinc levels of 12.9 and 0.4 ppm, respectively. All other major and micro-nutrients tested in a complete soil test were similar between the two sites. The soil is a medium texture, organic matter of 3.5%, and a pH of 7.3 to 7.9. This spring, I initiated an experiment on this field utilizing zinc sulfate at 0, 0.5, 1, 2, 4, 8, and 16 lb/acre of Zn and should have more information later this season. Zinc is a true micronutrient and only 0.05 lb/ton is normally removed by haying. Therefore, an application of 0.5 lb/acre should meet the requirements for a 3 ton/acre yield for 3 years.

Plant symptoms at a Lake Park, MN, site (where we believe the alfalfa-orchardgrass mixture responded to zinc fertilization) were stunted plants with a tinge of leaf yellowing. My first impression was that the problem at this site might have been poor nodulation, like a nitrogen deficiency, but there was no response to a strip application of urea even by the grass component. The symptoms occurred on most of the field except around low-lying areas. Symptoms on Nudellís field were most pronounced on hillsides, but they occurred in low-lying areas also.

We have documented four other alfalfa sites that have soil test zinc levels of <0.4 ppm this spring. The sites range from New York Mills, MN, to Valley City, ND, to Williston, ND. Producers in the Tioga, ND, area have commented that they see a "good" response to micronutrients foliarly applied.

In 2003, AGVISE Laboratories, Northwood, ND, published a summary of the percent of soil samples they handled that had less than 1.0 ppm zinc. They divided the state into eight regions. Their results indicated that 49% of the soil test samples from the northeast and up to 89% in the northwest had less than 1.0 ppm zinc. Other areas were between these extremes. This suggests that zinc deficiency might be much more common in all crops than what we believed in the past.

Itís suggested that you might want to observe some alfalfa fields in late July or early August to see if poor growth is occurring in areas of the field. If there are, obtain a soil sample and have the zinc level determined. If the soil test is less than 1 ppm, apply a test strip of zinc to see if a response occurs.

Dwain W. Meyer
Professor of Plant Science
dwain.meyer@ndsu.edu

 

FROST DAMAGE TO WINTER WHEAT

Just over a week ago, temperatures dipped into the low 20s (or below) in most regions of the state. Fortunately most of the spring-seeded cereal crops had not emerged or were not adversely affected by the freezing temperatures. Winter wheat, however, was well into tillering when this cold weather moved in. Most reports suggest that damage to winter wheat was limited to burning on the leaf tips. I did receive a few reports that the cold temperatures caused more significant damage, however, and I visited a winter wheat field near Mandan where most of the leaves had been burned back. Moreover, in the field margins, a significant proportion of the plants appeared to be completely dead. For those with winter wheat, after the warmer weather of the past week and recent rains, now is a good time to check winter wheat for any frost related damage, particularly if the crop is now jointing. Cereal crops are far more sensitive to freezing temperatures in the jointing stage as the growing point is above the surface of the soil.

During vegetative growth winter wheat and small grains in general are among the most frost tolerant of crops. Published reports suggest that wheat can tolerate temperatures as low as 12EF for a few hours without causing a significant yield los. Cereal crops are generally frost tolerant early in their growth cycle as their growing point is below the surface of the soils and is protected for the extremes in air temperature. Nevertheless, if temperatures are cold enough for a prolonged period, soils can be cooled to the point that the growing point can be damaged.

In the field where I observed significant frost damage, the soil was dry and the growing point was less than an inch deep due to shallow planting. These factors no doubt predisposed the plants to cold injury. To check for damage to the growing point of plants that have frost-damaged leaves, pull back the leaf tissue until you can see the growing point. A damaged growing point will appear brownish or water soaked.

Joel Ransom
NDSU Extension Agronomist
joel.ransom@ndsu.edu


NDSU Crop and Pest Report Home buttonTop of Page buttonTable of Contents buttonPrevious buttonNext button