To Spray or Not to Spray? That is the $100,000.00 Question!

Last July 10th was my daughter’s 25th birthday and we celebrated at our lake lot in B.C. You may be wondering what that has to do with spraying on our farm. Well, I didn’t understand either until last fall when I was riding in the combine with Roger and he said, “Do you see how the yield of this field is down by 10 bushels per acre? It’s because of scald. This barley should have been sprayed the first week of July when we were in B.C.” So when Jacqueline and her friends arrived at our lake lot this year for their annual trip, Roger and I only spent one day with them before coming home to spray the barley for scald, the canola for sclerotinia, and the wheat for glume blotch. Disease management involves making decisions related to numerous agronomic factors. Ways to control disease include crop rotations, planting rates & seed depth, soil fertility, and tillage or spraying fungicides.

Crop rotation is the oldest practice to control disease. The success of rotation depends upon the ability of the pathogen to survive in the absence of its host. At our farm we follow a rotation of wheat, wheat, canola, barley, barley, canola.

Planting rates & seed depth also help reduce disease. For example, a dense leaf canopy can creat a moist soil surface favourable to a pathogen such as sclerotinia. Planting depth can also affect root disease so knowing the optimum depth for the seed is important.

Soil nutrient levels also affect the crop’s susceptibility to disease. For example, too much nitrogen can result in leaf pathogens and inadequate phosphorous can predispose wheat to browning root rot. Soil testing and modern technology such as the section control for fertilizer on our seed drills make sure that our farm’s soil is balanced.

So what happens when we have done everything listed above and we still get a disease? Basically we have 3 options: 1) till our stubble under every fall and spring, 2) leave a field fallow (empty/no crop production for a year), or because we are a conventional farm, we have the choice to spray a fungicide. Now before I explain that fungicides won’t make you glow green at night, let me explain why we don’t do the first 2 options.

1) Tillage. If you read my May 18th Century 12 Farms Facebook post, you know that we practise Zero-Till for many reasons which are beneficial to the environment. Tilling the stubble under helps to reduce disease by burying the infected crop residue. However, tilling has many negative affects: soil erosion, less water conservation, less organic matter, and the burning of fossil fuels. A tractor burns 3200 litres of diesel per 640 acres (259 hectares).

2) Leave field fallow. The problem with this is two-fold. One, less food is being grown! And two, that empty section of land will grow weeds unless it is regularly tilled every 10 days to control the weeds. Remember the 3200 litres of diesel required to till 640 acres?

3) Our last resort is to spray fungicide. Farmers don’t enjoy spending over $100,000.00 on chemical and fuel (at least the sprayer only burns 50L of fuel per 640 acres). Nor do we enjoy spending summer hours in the field. But in order to grow a better quality crop (no one wants a diseased crop) we must spend the money and time. At our farm, we try to be extremely precise with the fungicide used. We have a contract with Climate Field View who upload satellite pics of our fields onto our computer. Those pictures show us the amount of vegetation and we can use that information to create a prescription for the chemical in the field. Roger circles and highlights areas where chemical is not needed due to poor plant stands or less disease-intensity. The computer program sends that information to the sprayer which then controls the spray nozzles depending upon their position in the field. Technology is helping us use less chemical!

This year we are spraying #Bayer Prosaro XTR on our barley before the disease reaches the top 2 leaves (flag leave -1 and flag leaf). A plant with disease in those 2 leaves produces a poor quality barley spike. Spraying Prosaro will stop the disease from spreading and produce a better quality barley and more yield. The LD50 (amount of substance required kill 50% of the population) is 2000 mg per kg. So for me, I would require 110,000 mg of chemical to have a 50% chance of dying. We spray 81.25 grams of active ingredient per acre. Assuming that all of the chemical landed solely on the barley spike (head), which it doesn’t, and assuming that the barley did not break the chemical down before harvest (which it does to an undectectable parts per billion), I would have to consume 1.35 acres, or 5,940 pounds of barley in one sitting to have a 50% chance of dieing from the chemical. I hope that puts your fears about fungicides to rest.

Controlling disease in crops is important to all farmers, organic and conventional. Our conventional farm has one more tool in our toolbox to combat disease. Thanks to modern technology we can produce healthy and safe crops to feed the world in a sustainable method that will leave the land in better condition for the generations to come! I just wish spray season didn’t interfere with lake season and my daughter’s birthday!