Agronomist Notes

There was little seeding progress made in our area as producers waited for fields to dry up, only to have another two inches of moisture come in the form of snow and rain. Many producers are 60-80% finished, with wheat to go, if they’re not switching over to barley. Crops seeded in the third week of May are now emerging. The early wheat is pushing a third leaf now, early canola has two leaves and barley is pushing a second leaf. I’ll start checking fields towards the end of this week, about one week behind compared to last year.

Recently, I’ve been out to investigate fields with emergence problems due to soil crusting. There are a few options for dealing with crusting issues after seeding. As far as pests go, I’ve started to scout for flea beetles, though I haven’t seen many in my travels. Even with this cooler weather it may be wise to check your field edges to be sure. You should also continue to monitor potential wireworm damage as there have been a few infested fields discovered lately.

This week’s issue focuses on estimating nitrogen loss in saturated fields, soil-crusting problems, and finally, flea beetle scouting and control.

Agronomy

Estimating Nitrogen Loss

According to research, the estimated denitrification loss of nitrate when the soil temperature is 55-60°F is 10% when soil is saturated for 5 days and 25% when saturated for 10 days (2-2.5% loss per day). Losses increase with warmer soils. Research conducted with late May to early June excess application of water on silt loam and clay loam soils indicated approximately 4-5 % loss of nitrate per day under saturated conditions.

To estimate N loss, first estimate the amount of ammonium converted to nitrate-N. By early May, with warmer than normal temperatures since application, one might assume fall anhydrous ammonia and fall manure ammonium to be 80-100% converted to nitrate and with early April pre-plant N application, approximately 50% converted to nitrate. Recent ammonium applications (within the last two weeks) would still be predominantly in the ammonium form, especially for anhydrous ammonia.

To find out how to calculate potential nitrogen loss click on: http://www.ipm.iastate.edu/ipm/icm/2007/5-14/estimating.html

Urea can be broken down into ammonia, carbon dioxide, and water through the action of an enzyme called urease. If this reaction takes place on the soil surface, the ammonia is susceptible to loss via volatilization. There is a lot of urease in crop residue, and its action is speeded up when temperatures are high and the soil surface is moist. High pH also increases loss of ammonia from urea. Application to warm, wet soils with residue and high pH on the surface can mean loss of up to half of the N from urea within a week. On the opposite end of the scale, in fields where tillage was done, there may be little or no loss of N from surface-applied urea even when it stays dry after application.

Source: http://www.ipm.uiuc.edu/bulletin/article.php?id=739

Soil Crusting: Problems and Solutions

Soil crusting results from rains breaking down soil aggregates into particles that cement into hard layers at the soil surface when drying occurs rapidly. The fields at risk were the ones seeded the first week of May into moist clay loam soils, followed by a 2-inch rain and above 20⁰C temperatures. It was a recipe for soil crusting in high disturbance systems. Fields with a history of summer fallow or tillage are most susceptible due to the loose fraction of soil on top that moves into soil pores after a rain and seals it off.

The goal of any crust-breaking maneuver is to crack the crust into small pieces and move them around slightly to let air and light into the soil below. Seedlings trapped under a crust will try to grow and elongate below the crust until they run out of stored energy from the seed. The cooler the weather, the longer the seedling can survive, unless a seedling disease infects it. The warmer the temperature, the faster the seedling will try to grow and the sooner it will run out of energy. It is important to deal with crusts soon after they form.

Source: http://www.smallgrains.org/Techfile/CRUSTING.HTM

Last week I had a producer phone me with a soil crusting issue and I suggested he try a spring tooth harrow, with the harrows set straight down to try and wiggle across the soil to bust up the crust. This was met with very limited success because the crust was too thick and hard and did more damage to the emerged plants than what was considered reasonable. He had reseeded 20 acres but wasn’t convinced it would be economical to re-seed wheat at the end of May. After checking the plant stand density, which was 16 plants ft² and suitable for a decent yield, the decision was made to leave it be. I had a similar field in 2004 and it went 60 bu/ac.

I’ve seen positive results from heavy harrowing right after seeding in moist clay loam soils. Heavy harrowing perpendicular to the seed row moves dry soil across the furrows to prevent the moist packed layer underneath from drying out. This method does confuse seeding depth but may be better than the alternative. I don’t know how successful you would be in a heavy clay soil because you may have too much compaction. If plants are emerging, a heavy harrow is not the answer because too much soil movement exposes seedling roots and tears apart emerged plants. Another solution may be to skim over a field with an empty double disc drill. I don’t know how successful this tool is but it sounds reasonably effective.

Flea Beetles

I haven’t seen many flea beetles in my travels this spring, however this is the time to be scouting for them. Actually, the best time to scout for flea beetles is at swathing time. If you noticed a large number of flea beetles while you where swathing last year, there’s a good chance those flea beetles might have migrated to adjacent fields of newly seeded canola.

Identification

Flea beetles attacking canola, mustard and rapeseed are small, elliptical or oval-shaped and less than 2.5 mm (0.1”) long. When disturbed they use their powerful hind legs to jump away like a flea and hence the name, flea beetle. Adult crucifer flea beetles are uniformly black with a metallic bluish sheen. The wing covers are randomly punctuated and the large hind legs are a dark amber colour.

Scouting

Scout fields daily in the spring, especially in areas with high flea beetle pressure last year. Assess damage to cotyledons and the first true leaves of seedlings. Continue scouting for the first 14 days after emergence, especially on sunny, calm days when temperatures exceed 14⁰C. Scouting twice a day may be warranted when weather conditions are ideal for flea beetle feeding.

Damage Assessment

Canola seedlings can withstand 50% leaf loss. However, flea beetles can locate, attack and quickly injure or destroy seedlings shortly after emergence. Therefore, the action threshold for flea beetle feeding on canola is when there is 25% defoliation and flea beetles are present. Applying controls at 25% defoliation will reduce the risk of flea beetle damage reaching a level where yield loss and plant development are substantially reduced.

For more leaf damage photos see this link: http://www.canola-council.org/fleabeetlemonitoring.aspx

Control

Under high beetle pressure and feeding damage, a delay of one to two days can result in loss of entire fields. If damage is limited to only the edge, spraying only part of the field may reduce flea beetle numbers. Apply insecticides during the sunny, warm part of the day when beetles are actively feeding on the plants. Canola plants that have reached the 4-leaf vegetative growth stage or beyond can tolerate more feeding damage, unless flea beetles are damaging the growing point.

During years when flea beetles are abundant through June, a yield loss of about 10% can be common even when the crop is protected with insecticidal seed treatments. Under these conditions a later foliar treatment (21 days after planting) may be necessary to protect the crop from re-infestation.

Source: Canola Council of Canada

Registered Insecticides

Decis: 40-60 ml/ac

Matador 120EC: 34 ml/ac

Sevin XLR: 200 ml/ac

Refer to the Crop Protection Guide for mixing and application instructions.

Wireworm Scouting & Control

Click on the link below to view last week’s Beyond Agronomy News issue on wireworms.

Link: http://www.beyondagronomy.com/newsletter/22_5_2007.htm

Market News

Wheat Usage Up

US Domestic wheat use is expected to increase 14% to the highest level in seven years, driven by a doubling of feed and residual use. Larger crops of Hard Red Winter and Soft Red Winter wheat and much higher corn prices relative to wheat, especially during the summer quarter (June-August 2007), will promote wheat feeding.

Source: USDA's Agricultural Outlook Forum 2007

Wheat Market Outlook

The market will continue to be led by weather across Australia, Ukraine, Russia, northern China, and the EU. US weather only has a small patch in NE Minnesota to be concerned with. International demand continues to pass on US offers, showing we are not yet competitively priced. This does not bode well for a market looking for a reason to rally. The Indian tender, which the USDA has bent over backwards to get a piece of, can offer a release valve for the US, but this is far fetched. Other international business remains hand to mouth offering no bullish momentum.

Source: Walsh Trading

CWB News

May 31 is the sign-up deadline for wheat deliveries under Series C contracts, including the CWB Identity Preserved Contract Program for hard white spring wheat. May 31 is also the deadline for 2006 fall cash advances to be issued for wheat, durum and barley under the Agriculture and Agri-Food Canada program administered by the CWB.

Source: www.cwb.com

Canadian Dollar

Over the last two weeks, the Canadian dollar has seen a good rally. Beginning near the .9090 levels, the Loonie has strengthened to the .9240 areas. Speculative buying has been much in evidence during the rally. Higher prices for commodities (gold and energy) have helped keep the rally in the Canadian. The fundamentals of Canada are bullish, and point to a higher value for the currency. However, the rally has become overextended and is due for a correction. Stand aside to wait for the correction to buy.

Source: Walsh Trading

Weekly USDA Global Crop Highlights

USDA's Joint Ag Weather Facility has provided weekly weather/crop highlights.

Link: http://www.agweb.com/get_article.aspx?src=gennews&pageid=136122

Seasonal Canola Pricing Patterns

The history of the WCE November canola contract indicates highs’ occurring in May with lows occurring in August, on average. In contrast, the May contract exhibits a pattern where highs occur in November and the lows in February, on average.

Source: http://www.ext.nodak.edu/extnews/newsrelease/2000/121400/10market.htm

Weather Outlook

My weather source predicts a wetter than normal June-July with June more likely to be wetter than July. This is due to the low sunspot activity, westerly stratospheric winds, low North American snow cover last winter and some residual El-Nino effects.