Maine Grain and Oilseed Newsletter, Vol. 1, No. 2 – April 2013

In this issue:

Dear Grower,

With planting season upon us in some parts of the state and quickly approaching in others, we wanted to get a couple more topics out to you, hence the mailing of our second newsletter only a week behind our first.

This newsletter contains information on seeding rates and grain drill calibration, aphid management, and a synopsis of UMaine field research and demonstration events for the upcoming season. We hope you will find this information useful.


Andrew Plant, Extension Ag. Educator
Ellen Mallory, Sustainable Ag. Specialist

57 Houlton Road, Presque Isle, ME 04769
207.764.3361 or 1.800.287.1462

Achieving Proper Seeding Rates for Small Grains and Oilseeds

Andrew Plant, Extension Agriculture Educator, UMaine Extension

Planting small grains and oilseed crops properly and on-time can produce a target population density that maximizes growth and cost efficiencies. Crop seeding rates can vary significantly owing to a number of different factors, including but not limited to variety, growing season, location, fertilization, quality of cleaning, and seed treatment use. Because of all these variables and their effects upon seed size, test weight, and vigor, it is not feasible to plant small grains simply based upon a bushels/acre seeding rate. Instead, seeding rates should be based upon crop-appropriate target populations, as can be seen in Table 1. There are several variables that farmers can account for when attempting to achieve these populations: seed viability (germination), historic stand loss of fields, number of seeds per pound, and grain drill operation (1).

Table 1. Target Population Densities for Selected Small Grains and Oilseed Crops.

Crop Plant Population Target*
Winter Wheat 0.90–1.00 million/acre
Spring Wheat 1.30–1.40 million/acre
Barley 1.25–1.30 million/acre
Oats 1.25–1.30 million/acre
Canola 0.3–0.6 million/acre
Soybean 0.13–0.175 million/acre

*Rates listed are typical for conventional production. For organic production, it is recommended to increase these rates by a range of 15%-25%.

By taking some simple measurements and using some basic math, you can determine an estimate of the proper seeding rate for your small grain and oilseed crops.


  • Jack
  • Buckets
  • Tarp/plastic
  • Tape measure
  • Scales
  • Calculator
  • Grain drill manual

Determining Seeding Rates:

In general, optimum planting dates for small grains in this part of Maine occur from roughly April 23 through May 8. To account for the decreased potential for tillering of small grains after this date, growers should increase their population targets by 1% for each day past May 8, up to a maximum of 1.6 million plants/ acre. Given the late start to our 2013 season, this rule should likely come into play. Past June 1, small grain growers should consider changing mindsets from one of harvesting a grain crop to one of producing a green manure plow-down. Oilseed crops do not follow the same general rule. Instead, planting should occur when soil temperatures reach a minimum of 40°F for canola or 50°F for soybeans.

The formula below depicts the variables growers should use to calculate the proper seeding rates of their small grains (1).

Seeding rate (lb/ac) = (target population/(1 – % stand loss))
seeds/lb x % germination
  1. Select proper target population per acre (example wheat @ 1.5 million plants/ac, May 15 sowing).
    (1.4 million + 1% for each day past May 8) = 1.5 million plants/ac
  2. Use germination percentage printed on seed lot tag (example 90%, convert to proportion = 0.9). Or do your own germination test.
  3. Use historical stand loss of field to be planted (example 10%, convert to proportion = 0.1).
  4. Count out 1000 seed pieces and weigh them (example 1000 seeds = 1.2 oz). This should be done for each different crop, each different variety, and each different known seed lot source.
  5. Convert to seeds per pound (example seeds/lb = (16/1.2)*1000= 13,333 seeds/lb).

Example: Target Seeding Rate:

(1,500,000/(1 – 0.1)) = 139 lb/acre
(13,333 x 0.9)

Calibrating The Grain Drill:

  1. Determine effective width of grain drill (e.g., 13 ft).
  2. Count seed tubes (e.g., 26 tubes at 6-in spacing).
  3. Measure diameter of drive wheel tire (for example 37 in = 3.08 ft).
    Estimate 1/10 acre planting.
    1/10 acre = 43560 sq ft per acre/10 = 4356 sq ft
    4356 sq ft/13 ft (width of drill) = 335 ft (the distance the drill must travel to cover 1/10 acre)
  4. Determine the number of revolutions of the tire in 335 ft.
    (Example: Circumference of tire = pi x diameter = 3.08 ft x 3.14159 = 9.68 ft/revolution, 335/9.68= 34.6 revolutions)
  5. Set your initial drill calibrations as specified in your manual to get the seed rate you want. (e.g., 140 lb/ac)
  6. Jack up the drive wheel so that it can spin freely, mark a line on the wheel, or use the valve stem of the tire for a reference point to count the number of times you spin it.
  7. Use a 5-gallon bucket, or a tarp, to catch seed dropping out of seed tubes. You will have to pull out seed tubes from openers and place them into buckets if checking individual tubes. The more seed tubes you collect seed from, the more accurate your estimate will be. (Record the number of seed tubes that you sample.)
  8. Fill bin with seed (only over the seed tubes you will be using to measure). Prime the seed tubes by spinning the drive wheel a few times unit seed starts to drop out of the tubes.
  9. Place your bucket/tarp under the tubes you will use and spin the drive wheel the number of revolutions you calculated above. (e.g., 34.6 revolutions; eyeball the 0.6.)
  10. Collect the seed from the buckets/tarp and weigh out.
    Example: We sampled a total of 6 seed tubes and had a total weight of 3.24 lb of seed in the bucket after our 34.6 revolutions.
    3.24 lb/6 seed tubes = 0.54 lb/ seed tube x 26 seed tubes = 14.04 lb/0.1ac = multiply by 10 for lb/ac = 140.4lb/ac seeding rate.
    You probably don’t need to adjust the seeding rate.
    Repeat 1–2 more times to determine reliability of the output. In the end, you want to be within 5% of your target seeding rate.
  11. If you need to adjust the setting on the drill, you can use a simple formula to get you closer to your target rate.
    For example, if you had the drill adjustment lever set at “20” (as that is where the manual suggested you set it), and you only got 120 lb/ac of seed, you need to set it at ”X” to get 140 lb/ac. Use the following formula:

New setting = A
lb/ac for target = B (e.g., 140 lb/ac)
Initial setting = C (ex.20)
lb/ac at this setting = D (e.g., 120lb/ac)
A = (B x C)/D
For this example:
A= (140 xc20)/120 = 23.33, so the new setting will be somewhere between 23 and 24, in order to get 140 lb/ac target rate.


  • Some drills are easier to calibrate than others, and all tend toward difficulty as they age.
  • Prior to calibration, make sure your drill is in good working order; fix, adjust, and verify that all components are in working condition.
  • Different crops tend to differ in the way they flow in a grain drill, and some may be more difficult to calibrate.
  • It is still important to ground-truth your calibration once you’re in the field planting. It’s also the time to check for uniform seeding depth. All of the small grains and soybeans should be seeded into a firm seedbed, at a depth of 1”-1.5”. Canola, owing to its small seed size, should be planted at a depth of 0.5”-1”.
  • For those that are using fertilizer and/or grass seeding boxes to apply fertility or underseeding at planting; the same methodology described above can be used to calibrate these rates as well, and can typically be done at the same time as the grain calibration. Just be sure to use separate catches for each component you’re calibrating.


If you choose to utilize a broadcaster to sow your small grains, there are several considerations to take into account. Broadcast sowings have less seed-to-soil contact than grain-drill sowings, so you will want to increase seeding rates by 10–20% over what you have calculated for a grain drill. As well, it is important to follow the broadcasting with a light harrowing or disking of the field in order to achieve appropriate soil contact to the seed. Uneven stands and lower yields are typical for broadcast sowings as compared to drills.

1. Wiersma, J.J. and Ransom, J.K. The Small Grains Field Guide (North Dakota State University and University of Minnesota, 2005), 27–33.

Treating Grain Crops for Aphids?

Jim Dwyer, Crops Specialist, UMaine Extension

There has been a great deal of discussion recently in regards to the possibility of treating grain crops in order to reduce the potential of non-potato colonizing aphids from moving from grain crops to potatoes. As the grain matures, these aphids search for a suitable alternate host and potentially spreading potato virus Y as they move through the potatoes.

One of the key questions is: Will there be aphids in the grain crop this year? In Maine, we do not always encounter significant populations of aphids every year in the small grain crops. On the other side, English grain aphid and bird cherry oat aphid, which can be found in Maine, can be significant vectors of PVY. If the populations of these aphids become high enough, they can impact the grain as well.

As one looks at the issue whether or not to treat the small grain crop, there are several other questions that come into consideration. How do I make the decision whether or not to treat? If I choose to treat, when? What is available to use if I choose to treat?

From an integrated pest management standpoint, a seed potato producer will want to evaluate where on the risk benefit scale treating small grains to reduce the potential for virus vectors is within their operation. If there are no aphids in the grains, then there is reduced risk; however, if there are aphids in the grains, the risk may be significantly increased. The question whether or not to treat is not black and white and the answer is rather subjective.

As seed growers wrestle with the question whether or not to treat small grains, growers will want to be aware that they do have several treatment options. Seed treatment with a systemic material or foliar treatments are both options that can be considered. If a grower would like to treat grain seed with a systemic material for aphid suppression, there are several considerations.

The neonicotinoids have several products available. These are the same class of materials which are used on potatoes as either an insecticide component of a seed treater or as an in-furrow material. Examples for use on grains would include Cruiser-Maxx Cereals, that has thiamethoxam as the insecticide component which is the same active ingredient as in Cruiser for potatoes; Nips-It, that has clothianidin as the insecticide, which is the same active ingredient as in Belay; and Gaucho 600 that has imidacloprid, which is the same insecticide ingredient as in Admire. If considering using a seed treatment material, please read and follow the label instructions; and very importantly, please use only the product labeled for the intended use. These products used as a small grain seed treatment, and depending upon the product and environmental conditions, should provide approximately 40 to 60 days residual aphid control.

For early planted grain crops, because of the timing and duration of the residual activity, the aphid suppression activity may be low as we enter the mid-portion of the potato season. As grain continues to grow, growers will want to be actively scouting to determine if the aphid population has been suppressed. For late-planted grain, many of the products should provide suppression of the aphid population through an important part of the season and thus reducing the potential for large aphid populations to build-up within the small grain crops. As with any pest related situation, growers will want to scout the grain and be sure that the population is being managed rather than making an assumption.

For growers who would like to wait and see if aphids do buildup in the grain crop, there are several foliar insecticides available for consideration. Materials available include cyfluthrin sold as Baythroid; methomyl sold as Lannate; lambda-cyhalothrin sold as Warrior; and malathion sold as various formulations. Please be aware that there may be additional materials with the same active ingredient that may or may not be registered for use on small grains. Registered materials may be applied as a foliar application being sure to adhere to all pesticide label requirements. Applicators should also be aware that best foliar control is achieved before the insects begin to roll the leaves. Once the crop has begun the boot stage, some products may only suppress the aphid population.

The question as to what is an economic threshold for aphids in grains depends if you are looking to suppress aphids from damaging the grain or as a vector for viruses impacting potatoes. To control aphids as a virus vector in potatoes, there is no definitive information on which to base an economic threshold. For grain, the greatest risk of yield loss from aphid feeding damage is from the vegetative to boot stage. North Dakota State University suggests as a threshold for aphids on oats and barley, when 85% of the stems have at least one aphid or when there is 12 to 15 aphids per stem prior to complete heading: 2012 Insect Management Guide

(Mention of a trade name is not intended as recommendation or an endorsement.)

2013 Small Grain and Oilseed Research Trials and Field Days

UMaine Sustainable Ag Field DayThis season we have a number of research trials and field days planned that focus on small grains and oilseeds. Feel free to check on the progress of the trials throughout the season, and be sure to mark your calendars for the field days.

Small Grains and Oilseed Field Days

June 26: UMaine Sustainable Agriculture Field Day
To feature research trials on winter and spring wheat varieties, in-season diagnostic tests for winter grains, planting date effects on winter canola and winter wheat, and organic feed grain crops.
4:30-7:30 p.m.
UMaine Rogers Farm, Stillwater, Maine

July 9: Organic Feed Grain Field Day and BBQ
To feature demonstration plots of different organic feed grain crops, crop mixes, and production methods. Reps from Organic Valley will be on hand and will provide the BBQ.
Evening (time to be determined)
Aroostook Farm, Presque Isle, Maine

Small Grains and Oilseed Research Trials

The following trials are being conducted at the UMaine Aroostook Research Farm in Presque Isle, the UMaine Rogers Research Farm in Stillwater, and on growers’ fields throughout Maine. In some cases, collaborators in Vermont are conducting replicate trials at the Borderview Research Farm in Alburgh, Vermont.

Organic Feed Grain Demonstrations
To evaluate various feed grain crops and production methods including barley and field pea varieties, barley-field pea mixes, planting densities and arrangements for barley and soybeans, and undersowing options.
Location: UMaine Aroostook Research Farm and Rogers Research Farm
Contact: Ellen Mallory

Conventional Soybean Variety Trial
Evaluate currently marketed soybean varieties for maturity, disease, yield and bean moisture.
Location: Crouseville, ME
Contact: Andrew Plant

Winter and Spring Wheat Variety Trials
Compare 18 winter and 17 spring varieties of hard red wheat for agronomic characteristics, baking performance, and taste.
Locations: Winter variety trials are at the Rogers Research Farm, Nature’s Circle Farm in Houlton, and in Vermont. Spring variety trials are at Rainbow Valley Farm in Sidney, the Aroostook Research Farm, and in Vermont.
Contact: Ellen Mallory

Foliar Growth Regulator for Barley
Evaluate a commercially available plant growth regulator (PGR) containing gibberellic acid for its use in small grains to promote growth, tillering, and yield.
Location: Presque Isle, ME
Contact: Andrew Plant

Systemic Insecticide Seed Treatments for Barley and Oats
Evaluate crop and insect response to inclusion of systemic fungicide, systemic fungicide + insecticide, in comparison to untreated grain seed.
Location: Aroostook Research Farm
Contact: Andrew Plant

Winter Canola Production
Evaluate winter canola production potential for Northern New England. Studies include variety, fertility, seeding rate, and planting date trials.
Location: Aroostook Research Farm, Rogers Research Farm
Contact: John Jemison

In-Season Diagnostic Tests for Winter Grains
Evaluate the early spring tiller count test (done at Feekes 3) and the tissue nitrogen test (done at Feekes 4-5) as decision tools to guide spring nitrogen topdress application.
Locations: UMaine Rogers Research Farm and Vermont
Contact: Ellen Mallory

Winter Wheat Planting Date and Rate
Evaluate winter wheat varieties for tolerance to late planting, and assess economically optimal seeding rates.
Locations: UMaine Rogers Research Farm and Vermont
Contact: Ellen Mallory

Organic Nitrogen Sources for Winter and Spring Wheat
Compare dairy manure, poultry litter, chicken layer manure, and clover plowdown for their ability to supply nitrogen to winter and spring wheat crops and produce adequate grain protein levels.
Location: UMaine Rogers Research Farm
Contact: Ellen Mallory

Microbial Inoculant Effects on Spring Wheat Grain Yield and Protein
Compare 1 purchased mycorhizal inoculant (MycoApply®, Mycorrhizal Applications Inc., Grants Pass, OR) and two farm-produced inoculants (arbuscular mycorrhizal fungi and indigenous micro-organism) for their effects on wheat growth, nutrient uptake, grain yield, and grain protein.
Location: UMaine Rogers Research Farm
Contact: Ellen Mallory

Information on this website is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

© 2013

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