Agronomist Notes

Another week and another 3.6 inches of rain topped up the rain gauge, bringing our 30-day total to 8.1 inches! And so we face yet another challenging spray season. Thankfully the weather looks promising for the next five days although nighttime temperatures may be critically low in a few areas. In general, the crops are about a week behind the normal pace because of the cooler than normal May-June period.

I’ve scouted over 21,000 acres of wheat, barley and canola so far with another 7,000 to go. What I’ve noticed the most is the nitrate and sulphate leaching in the lighter land and oxygen-starved chlorotic plants in the heavier clay land. Leaf disease pressure has backed off with the very recent warm weather although consecutive wheat or barley rotations are still at risk. The cool and wet spring has left my area with very little insect pressure except on some chemfallow fields which have shown increased flea beetle damage.

My post-herbicides checks have found adequate but slow control of wild oats and only satisfactory control with contact herbicides such as Buctril M, Thumper and Unity. Over all, I’m still very impressed with the results, given the envelope we’ve been pushing to get our spraying done in a timely manner. The forecasted +200C weather may close our crop and weed staging window quickly so be sure to do everything possible to increase your spraying efficiencies.

This week we’ll discuss the rules of engagement for maximizing herbicide efficacy when spraying outside ideal conditions and how environment affects herbicide performance.  We’ll also discuss cutting herbicide rates and what factors the companies consider when they write a label. We’ll take a look at the nitrate and sulphate leaching I’ve experienced on my own farm this spring, as well as growing degree days and where we sit on average. In Market News, we’ll find out what’s going on with crop weather around the world.    

Crop Staging Area (Calgary to Drumheller to Three Hills)

Date Seeded:	April 23-31	May 1-7	May 8-15
Wheat	5 leaf, 2 tiller	4 leaf, 2 tiller	3 leaf, 1 tiller
Canola	6-leaf	5-leaf	4-leaf
Barley	5-leaf, 2 tiller	4-leaf, 2 tiller	3-leaf, 1 tiller
Peas	9th node	7th node	5th node

Temperature and Herbicide Efficacy

In order to maximize the herbicide efficacy and reduce crop injury we should “ideally” be spraying at temperatures between 180C and 280C. When spraying outside this window we increase the risk of reduced weed control and crop injury. Often we find ourselves spraying early morning or early evening to avoid the wind. If you are thinking of spraying outside this window, understanding the rules of engagement will help you maximize your herbicide efficacy.

• Do not spray contact (bromoxynil) herbicides like Buctril M, Thumper, Benchmark, Unity and Liberty in temperatures below 150C or above 280C. 
• Do not spray grassy (wild oat) herbicides in late evening when night time temperatures fall below 70C. This increases the risk of crop injury. 
• Control of grasses under flooding or prolonged cool temperatures below 150C increases the risk of escapes or re-tillering of grassy weeds.
• In cool weather choose products containing 2,4-D, MCPA, dicamba (Banvel), clopyralid (Lontrel) and fluroxypyr (Attain) which have adequate crop safety and provide similar weed control across a wide range of temperatures.
• Products like Achieve Liquid and Poast Ultra are photosensitive and break down quickly under high sunlight conditions. Warm and cloudy conditions during and following application can maximize the efficacy of these products.

Source: http://www.smallgrains.org/springwh/Summer07/weed/weed.html

Herbicides 101: Environmental Effects

Metabolism: Crops often metabolize herbicides easily during warm humid conditions but metabolism slows during cool or cold conditions. This extends the amount of time required to degrade herbicides in plants. Rapid degradation under warm conditions allows crop plants to escape herbicide injury. Herbicides may be sprayed following cold night-time temperatures if day-time temperatures warm to at least 150C.

Photosensitivity: Sunlight inactivates some herbicides by ultraviolet (UV) light. Liquid Achieve, Poast, and Select are highly susceptible to UV light and will degrade rapidly if applied during mid-day or if left in non-metal spray tanks for an extended period of time. To avoid UV breakdown, apply soon after mixing with the correct adjuvant, which enhances and speeds absorption.

Grass and broadleaf weeds are controlled more effectively when plants are actively growing. Liquid Achieve and other Group 1 (ACCase) grass herbicides generally provide more consistent and greater grass control in warm, dry conditions compared with cool, wet conditions. Other ACCase herbicides, such as Assure II, Poast, and Centurion, also control grasses better in warm weather when grasses are actively growing. Cool or cold conditions at or following application of ACCase herbicides such as Liquid Achieve may increase injury to wheat.

Cold temperatures, including freezing conditions following application of ALS herbicides (Group 2’s) may increase crop injury of labelled crops with little effect on weed control. To avoid crop injury and improve herbicide efficacy, delay applying fenoxaprop (Puma Super, Fusion) ALS herbicides until daytime temperatures exceed 15 0C and after active plant growth resumes. Basagran, Liberty and Gramoxzone are less likely to cause crop injury when cold temperatures follow application but less weed control may result.

Products such as 2,4-D, MCPA, dicamba, clopyralid (Lontrel), fluroxypyr (Attain) have adequate crop safety and provide similar weed control across a wide range of temperatures, but weed death is slowed when cold temperatures follow application.
Source: http://www.smallgrains.org/springwh/Summer07/weed/weed.html

Using Herbicides at Reduced Rates

Ideally, control of target weeds at the lowest herbicide rate provides the greatest return over herbicide and application costs. This “best” herbicide rate will be different for every combination of herbicide-weed-environment-adjuvant combination. Sometimes, the “best” rate will be lower than the lowest rate on the herbicide label. The following variables are considered by companies when they write a label.

Weed Size and Crop Size. Companies make an assumption of weed and crop size at herbicide application. Small weeds are more susceptible to herbicides than large weeds, but small crop plants may also be more susceptible. Reduced herbicide rates may be used if herbicides are applied to weeds smaller than listed on label. The crop will also probably be smaller, so knowledge of crop safety also is needed.

Environment. Companies write labels that cover most environments in which herbicides are used. Environment has a large influence on the efficacy of herbicides. Herbicide rates may be reduced under ideal environmental but special knowledge is needed on the environment-herbicide interaction.

Adjuvants. Most post-emergent herbicides require addition of adjuvants such as surfactants, crop oils, methylated seed oils, or fertilizer. Adjuvant information is fairly general on pesticide labels to address adequate weed control under most situations. Herbicide rates sometimes can be reduced by using adjuvants that are highly effective with a specific herbicide but additional knowledge is needed. The herbicide-adjuvant combination must be safe on the crop as well as provide good weed control.

Method of Application. Special knowledge of the best application method for a specific herbicide and situation may allow a reduction in herbicide rate.

Weed Species. Labels sometimes list weed species separately on the label with different rates for different weeds. Herbicide rates may be reduced when highly susceptible weed species are present.

Performance Complaints. Using reduced rates may result in poor weed control. The user assumes all risk and liability of unacceptable weed control when less than labeled rates are used.

Are Low Rates Legal? A herbicide user can legally choose a rate lower than listed on the herbicide label unless the label specifically prohibits low rates. However, the company has no obligation to support herbicide efficacy when the application rate was less than labeled rates. Herbicide users should not expect a company representative to provide any comfort or assistance if weed control is less than expected from a rate of herbicide that is less than the labeled rate.
Source: http://www.smallgrains.org/springwh/Summer07/weed/weed.html

Initial Observations of Ammonium Sulphate on Wheat

The last few years we’ve experimented with broadcasting ammonium sulphate (21-0-0-24) fines in the fall as a cheaper source of sulphur before canola. Not only less costly, it also reduces 80 to 100 lbs of product from our spring blend which increases our acres seeded per fill. I was curious to see how well a broadcasted ammonium sulphate application would work as a nitrogen source for my wheat. Understanding the highly mobile nature of nitrate and sulphate and the associated risks of leaching or runoff, I went ahead with the application.

I broadcasted 315 lbs of 21-0-0-24 in March, 2008 giving me 66 lbs of nitrogen and 75 lbs of sulphur per acre. I applied 40 lbs of 11-52-0-0 with the seed on May 3rd, bringing my nitrogen total to 70 lbs per acre. The soil texture is a heavy clay loam with gently rolling topography. We’ve received eight inches of rain since May 1st.

In the picture above, the crop shows chlorotic (yellowish) top and bottom leaves. The symptoms are restricted to the knolls, of which there are several, maybe covering 3% of the total field. A tissue test was taken June 5th to determine if we lacked any nutrients. The results came back with nitrogen and sulphur being deficient even after applying 70 lbs of nitrogen and 75 lbs of sulphur! The recommendation is to apply 30 lbs of nitrogen and 10 lbs of sulphur.
My current assessment is that the risks associated with broadcasting ammonium sulphate are too great on this field to apply that technique again. It also shows the risk of sulphate and nitrogen moving off target when we broadcast it before canola, even on gently rolling terrain. Had the crop been canola, we wouldn’t have noticed the sulphur deficiency and would have blamed the poor growth on topography. I’ll continue to assess the progress of this field and follow up with future results. SL

Growing Degree Days

The cool weather this spring has definitely taken its toll on crop maturity, but by how much?  Crop maturity is directly affected by the number of growing degree days we receive each year. Growing degree days is simply the calculation of the highest daily temperature plus the lowest daily temperature divided by two and subtracting five (Ex: 200C + 100C ÷ 2 - 5 = 10 GGD). You subtract five because it is assumed that plant growth does not occur at less than five degrees Celsius.

Growing Degree Days from May 1st to June 15th:
2008: 345
2007: 384
2006: 437
2005: 365
2004: 314
5 Year Average: 369

To date we are 6.5% below the five year average for crop maturity and on track for the second coldest year since 2004. It seems like we’re behind, and we are, but not by a large margin. We can make up a lot of ground in July-August if hot temperatures occur. If they don’t we may be at risk for fall frosts. I’ll continue to monitor and worst case scenario, we may have to prepare for a swathing program this fall. We’re a long way from harvest but I’ll keep you updated. SL

Market News

International Crop and Weather Highlights

Europe: Heavy showers across central and western Europe provide favorable to locally excessive moisture for filling winter wheat, barley and rapeseed but maintain crop quality concerns. Persistent dryness in northeastern Europe is untimely for winter wheat and barley. Showers ease short-term dryness in the Balkans, benefiting filling winter grains and vegetative corn.

Former Soviet Union: Showers maintain favorable moisture In Ukraine and western Russia for winter grains and spring-sown crops, although unseasonably cool weather slows summer crop emergence and development. Showers and cooler weather gradually overspread major spring wheat producing areas of Russia and Kazakhstan, favoring crop emergence and early establishment.

Middle East: Dry weather in Iran further reduces prospects for filling winter grains but favors early harvesting.

East Asia: Mostly dry weather aids winter wheat harvesting across the North China Plain. Scattered showers maintain favorable soil moisture for corn and soybeans in Manchuria and throughout the south.

Southeast Asia: An active monsoon brings widespread showers to corn in Thailand and the Philippines.

South Asia: The monsoon arrives up to three weeks early in northern portions of India and Pakistan, providing early-season moisture to key rain-fed soybean areas.

Australia: In Queensland and northern New South Wales, widespread showers benefit vegetative winter wheat. In central and southern New South Wales, drought hampers winter grain planting and development. Scattered showers maintain local moisture supplies in Victoria and South Australia. Mostly dry weather covers Western Australia, but soil moisture is generally adequate for winter grains.

South America: Rain maintains overall favorable moisture for winter wheat establishment in southern Brazil. In Argentina, cool, dry weather aids the final stages of summer grain and oilseed harvesting. Rain is needed for winter wheat establishment in most major production areas.

Canada: Beneficial rain brings some drought relief to emerging spring grains and oilseeds in eastern Saskatchewan and Manitoba.

Mexico: Rain continues in the southeast, but unseasonable dryness persists in western corn belt of the southern plateau.

Barley Prices May Not Go Much Higher

If markets were only about supply, the barley market would have the potential to be very strong this coming year. Ending stocks at the end of the 2007-08 marketing year are expected to be at record-low levels as the strongest exports in over 10 years helped offset sagging domestic demand. And despite the tight supplies, barley acres are forecast to be 10 per cent below year-ago levels.
Full story: http://www.grainews.ca/issues/isarticle.asp?id=85694&issue=06132008&PC=FBC&story_id=&link_targ=DailyNews&link_source=aypr_GRN

Drought Threatening South Dakota and Montana Wheat Crops

More than half of Montana's wheat fields are withering an early season drought, putting some $671 million worth of wheat at risk, new state agriculture statistics show. The winter wheat harvest in South Dakota is forecast at 82.3 million bushels. That is an increase of 7 percent from last month's Agricultural Statistics Service estimate, but it's 13 percent smaller than last year's record production of 95 million bushels. Winter wheat yield in the state is forecast to average 47 bushels an acre, up three bushels from last month but one bushel less than last year.

Source: http://www.redorbit.com/news/science/1430565/drought_threatening_wheat_crop/
Source: http://www.zwire.com/site/news.cfm?newsid=19769528&BRD=1302&PAG=461&dept_id=181978&rfi=6

Biblical Pest Invades Russia’s South

An emergency has been declared across several regions of southern Russia because of an insect. Swarms of locusts have invaded the area, putting the harvest in serious danger. Five regions in the south have reported locust outbreaks, though the Volgograd region is suffering most. The source may be Kazakhstan. A severe locust infestation there is threatening food shortages and all wheat exports have been banned.
Full story: http://www.russiatoday.ru/news/news/26230