Agronomist Notes
Another 2 to 3.5 inches of rain fell over our area last week, and in spite of the moisture, we managed to get a lot of spraying done in a short time. The major issues to be aware of this week are potential denitrification losses in saturated fields, leaf diseases in wheat and barley, and herbicide application windows closing in. I’m starting to see heavy tan spot on wheat fields planted into wheat stubble and net blotch in barley, which is quite normal given the moisture conditions. The top leaves remain healthy so I’m not too concerned at this time, but it’s something we’ll have to watch as the crops progress.
The majority of canola is anywhere from 4 to 5 leaf and some starting to bolt, which is exciting for this time of year considering the spring we’ve had. The early seeded wheat has 5 leaves, 2 tillers with the majority of wheat sitting with 4 leaves and 2 tillers. The early seeded barley now has 5 leaves and 3 tillers with the majority at 4 leaves and 2 tillers. Early June seeded wheat and barley are at 2 leaves and pushing a third.
This week we will discuss options for controlling disease at herbicide timing and whether it is economical at early leaf stages. We’ll also cover risks and rewards of tank-mixing herbicides with other products such as fungicides, insecticides and fertilizer. Finally, we’ll take a look at nutrient deficiency symptoms in wheat, barley and canola. â– SL
Agronomy
Should I apply a fungicide at herbicide timing?
The quick and dirty answer is no on most occasions, however there are times when a fungicide can provide an economic benefit prior to flag leaf emergence or at herbicide timing. An early fungicide application may be warranted if:
- The crop was planted into infested cereal stubble (e.g. wheat on wheat stubble);
- The crop has a very dense and moist canopy (e.g. reduced air flow);
- Lesions are observed on the newest leaf growth;
- The lesions are caused by stripe or leaf rust;
- The crop is of high value (e.g. seed growers) and the cost of control is less of an issue.
* If you have checked at least 3 of these, then there may be an economic advantage to applying fungicide at the seedling stage
Cereals in the seedling and vegetative stages are most susceptible to leaf spots because they are located close to the ground where conditions are more humid and are closer to disease inoculum from infected stubble. This is why the most early and severe symptoms are seen in cereal crops planted into the same type of cereal stubble.
It is essential to accurately diagnose whether the symptoms observed are caused by disease pathogens. Yellowing, spotting, streaking and leaf death could be the result of other problems including root disease, nitrogen deficiency, insect damage, herbicide injury, heat banding or frost. At first glance, a crop may look unhealthy if the oldest leaves are infected with disease or have other injury. However, it is important to look at the new leaf growth. If the new growth is healthy and the overall crop density is sufficient, the crop should quickly recover.
Source: Penny Pearse, Saskatchewan Agriculture & Food
Tank Mixing Pesticides: Positive or Negative?
Applying a tank mix of herbicides, fungicides, insecticides or liquid fertilizer can save time, labor, energy and equipment costs. Pesticide combinations usually alter plant absorption and translocation as well as metabolism and toxicity at the site of action of one or more of the mixed products. Not all changes are for the better. Negative effects can occur such as reduced pest control, increased damage to non-target plants (phytotoxicity and incompatibility problems between materials.
There are basically four types of interactions that change the efficacy of pesticide combinations:
- Additive effects occur when mixing two pesticides provide the same response as the combined effects of each material when applied alone. The products neither hurt nor enhance each other. Such mixes save time, labor and equipment use.
- Synergistic responses are often confused with additive effects and occur when two pesticides provide a greater response than the added effects of each material when applied separately. Unlike additive effects, the chemicals in a synergistic combination are not neutral toward each other. Rather, they interact in some way that increases their effect and may increase control. With true synergism, you can often reduce pesticide application rates without sacrificing control.
- Antagonism. When two pesticides applied together produce less control than if you applied each material separately is called antagonism. In addition to reducing control, antagonistic responses also may increase phytotoxicity to plants. When the herbicides Assert® (imazamethabenz-methyl) and Banvel® (dicamba) are mixed together, they negatively affect each other’s performance.
- Enhancement is another type of interaction, but not between two pesticides. Enhancement occurs when a pesticide is mixed with an additive to provide a greater response than if you applied the pesticide alone. A common example of enhancement is mixing an adjuvant with a pesticide.
Source: http://www.co.fergus.mt.us/weed/Pesticide%20Interactions%20and%20Compatibility.htm
Tank Mixing Pesticides Can Cause Crop Injury
The pictures below show signs of phytotoxicity or leaf burn from applying a tank mix of Group 1 herbicide with a fungicide. I’m adding this picture because although the products can be mixed together in the tank without issue, there can be significant harmful effects when applied. This seemingly harmless mixture of a Group 1 herbicide and a Strobilurin based fungicide caused significant leaf burn to the wild oats and the wheat.
When you apply a systemic herbicide like a Group I with a systemic fungicide like a Strobilurin you have what I liken to a traffic jam, where both products compete for the same entrance into the tunnel and inevitably something’s got to give. However, the family of Propiconazole fungicides such as Tilt, Bumper and Pivot are registered for tank mixing with 2,4-D Amine, MCPA Amine, Buctril M, Pardner and Horizon 240EC. The reason Propiconazole products can be tank mixed with a Group 1 herbicide like Horizon is because this class of fungicide is only partially systemic, thus reducing the amount of “traffic” entering the plant at once.
Leaf burn from applying a tank mix of Group 1 herbicide with a Strobilurin fungicide on wild oats (left) and wheat (right). Photo source: Syngenta.
Early Application of Fungicides at Herbicide Timing
Tan spot establishes early in the growing season and if environmental conditions are optimum, it can rapidly spread. Uncontrolled, it can quickly work its way up the plant canopy. Early season fungicides that can be used on tan spot include: Tilt, Bumper, Stratego, Headline and Quilt. All of these fungicides are good on leaf spot diseases at the tillering leaf stage.
Generally, these fungicides are applied at a half label rate, and the best response is seen when wheat is planted into a previous wheat field. For example, an early season application of fungicide on Reeder hard red spring wheat plots planted into wheat stubble had the following responses: using 5 ounces of Stratego yielded 47 bu/ac; using 3 ounces of Headline yielded 44 bu/ac; using 2 ounces of Tilt yielded 46 bu/ac and untreated plots yielded 43 bu/ac.
An early season (4-5 leaf) application of fungicides on tan spot in hard red spring wheat plots in Fargo (wheat planted into wheat stubble) in 2006 yielded 52.6 bu/ac on untreated fields; but with 4 ounces of Stratego plus other herbicides the yield increased to 56.6 bu/ac. An early season (4-5 leaf) application of 3 ounces of Headline on tan spot in several varieties of wheat showed a yield increase of 2.5 bushels, 71.4 bu/ac on untreated to 73.9 on treated fields.
Do you see signs of nutrient deficiency?
If you’re seeing visual signs of crop stress and would like to discover what’s causing it, I have included a link to common wheat, barley and canola nutrient deficiency symptoms to help you. Remember to follow up your suspicions with a plant tissue sample to confirm what you’re seeing. To give you an example of the value of plant tissue sampling, I had portions of a 600-acre winter wheat field showing signs of what I thought was sulphur and nitrogen deficiency. After 8 inches of rain in May, the top and bottom leaves were yellowing on about 200 acres of the sandy loam knolls. After a plant tissue sample I was able to confirm the deficiency and apply 150 lbs/ac of ammonium sulphate to correct the problem. You could see the crop start to recover within a week’s time. The difference that $26/ac of broadcast ammonium sulphate made on 200 acres at this point looks to be a 30 bu/ac or, at today’s value, $150/ac!
Check out these photo galleries of nutrient deficiency:
Wheat http://www.back-to-basics.net/nds/crops/wheat.htm
Barley http://www.hbci.com/~wenonah/min-def/barley.htm
Canola http://www.back-to-basics.net/nds/crops/canola.htm
Market News
Wheat Rally Short Lived
The recent rally in wheat has everyone wondering how long will it continue. To sum up a lead market analyst for DTN, he said a change in supply creates a short-term change in price while a change in demand creates a long-term change in price. What we’re seeing right now is the short-term change in supply driving the market. A good example is the current corn market. We have a demand driven market with historically high prices that have lasted from December 2006 continuing today. The wheat market however is in a short supply situation, which typically leads to short-term price fluctuations that don't last. Another sign of a short lived price spike is the wide carry in the new crop wheat contracts, which indicates a bearish supply and demand situation. The recent USDA report predicted world wheat ending stocks to be down by one million tonnes, but it also coincides with a predicted drop in world demand for wheat that everyone is ignoring. Therefore, the recent rally should be short lived. SL
The historical chart below is taken from the 1996 December wheat futures. The analysts are comparing 1996 to today’s market with supply driving prices both years. Take a look at the drop in March on both charts with prices climbing to new highs in May and June after the USDA dropped wheat stock estimates in both years. The problem that followed was prices continued to drop after the high prices rationed world demand. We may not see as sharp of a price drop today as in 1996 (due to the tightest world ending stocks in thirty years), but countries like Egypt are now backing away from wheat deals due to current high prices. SL
2007-08 EU Grain Crop Estimate Down
Strategie Grains cut its estimate for the European Union’s 2007-08 cereal crop by 3.1 million metric tons from the previous estimate to 276.5 million tons. Hot and dry weather in April in Romania, Hungary, Germany and Bulgaria and to a smaller extent Italy, Greece and the Czech Republic, were the main countries where crops were affected by the heat.
Source: CBOT News
Wheat Prices: Fundamental News
According to some analysts, the wheat market is overbought and due for correction. However, with US crop production and carryout ideas declining, the market is able to sustain strength in spite of seasonal weakness in June. There are indications that the US wheat crop did not recover as much as expected from the Easter freeze, with recent excessive precipitation delaying harvest only adding to the production decline.
The drought in Ukraine and southern Russia is still a major concern. Ukraine’s Ag minister announced Thursday that they are likely to lose 10 million metric tons of grain in this year’s harvest, out of a total 38 million metric tons that were forecast by the agriculture ministry earlier. Officials still plan on suspending exports until grain reserves can be built to meet domestic needs first.
Source: FIMAT
World Oilseed Production Down
In 2007/08, world oilseed output may fall more than 5 million metric tons to 399 million, as larger rapeseed crops are offset by production declines for soybeans and other oilseeds. In most countries, soybean production this year will be affected by a strong inclination to plant corn.
Full story: http://www.cattlenetwork.com/content.asp?contentid=137157
World Feed Barley Prices
The world market is driving barley prices, and for the first time, because of or during deregulation of the market in Australia and Canada, we're seeing what's happening in the world market reflected more fully in the cash prices. One of the factors pushing up the price is quite a severe drought in Russia and the Ukraine - they usually supply discounted barley into the Middle Eastern markets. Another reason is that the United States and European grain futures markets are all heading up because of falling crop prospects in the US and EU.
Full story: http://nqr.farmonline.com.au/news_daily.asp?ag_id=43103
