Tone Ag Consulting Ltd.

I recently toured a greenhouse that’s growing over two acres of cucumbers. White flies are a big problem for greenhouse cucumbers, but not for field cucumbers.  Out in the fields, white flies are quickly devoured by predatory insects, so they rarely cause any significant damage to cucumbers. The most cost-effective solution for controlling white flies in the greenhouse is to bring the white flies’ natural predators in.

Something that was really driven home to me this summer is the importance of predators in controlling pests. I walked fields that had a lot of soybean aphids and a lot of ladybugs. Soybean aphids are native to Asia. In North America they over-winter in the North Central United States and fly or are carried by winds to Manitoba. The aphids were below the economic threshold, so I advised not spraying. As I walked the fields through the summer I saw more and more ladybugs and fewer and fewer aphids.  The natural predators had prevailed and the farmer was saved the cost and hassle of application.

Most pesticides are not very selective. They will kill pretty much any kind of insect. This can lead to situations where you spray for a pest that’s devouring your crop but you wind up killing its predators instead. This leads to a friendly environment for the pests and a bad situation becoming worse. There are some more selective pesticides out there, but most of them are still in the early phases of development.

One reason for waiting for the economic threshold is to avoid this kind of situation, where a pesticide application not only costs you the expense of application but also costs you yield. By knocking out the predators you’ve made your field friendlier for the pests. There is a Blackberry app from Ontario that has you enter the number of aphids and the number of predators to calculate a customized economic threshold.

There will always be more pests than predators, for the same reason that there are more deer than wolves. If you only see one ladybug for every thousand aphids, the populations are in balance.  An adult ladybug can eat up to one thousand aphids per day.

It’s usually not worth the expense to bring in predators. Gathering enough ladybugs to have an effect on a field scale is a pretty big job. In Manitoba, the economic action threshold for soybeans is 250 aphids per plant with an increasing population. Target soybean populations are generally over 180,000 soybeans per acre. With the aphid population doubling in about a week, you’d need 45,000 ladybugs per acre to keep the levels down.  I found prices for ladybugs online at $17 per thousand. Even if you could buy enough ladybugs, you’d be paying $765 per acre for ladybug control of aphids.  Then there’s the problem of distributing all those ladybugs…

The biggest thing you can do to encourage natural predators is being very careful with pesticides. Walk your fields frequently, keep an eye on the economic thresholds, choose your pesticides wisely, and apply them carefully.

Fall is a great time to apply fertilizer. When the fields are ready to seed in spring, the last thing you want to do is delay seeding while you put down fertilizer. In fall, there’s usually plenty of time between when the crop is off and snowfall to put in fertilizer. Fertilizer prices are usually better in fall than in spring and if you apply it right away you don’t have to worry about storing fertilizer through the winter. The soil is generally much nicer to work on in fall than in spring – most falls you won’t leave big ruts and mess up your seedbed.

So why not just apply fertilizer in the fall and relax?

The biggest problem with fall application of fertilizer is that the longer the time between application and plant uptake, the less fertilizer remains available to the plant. Nitrogen fertilizer is especially vulnerable to losses. The primary cause of loss is denitrification, where the nitrate converts to nitrogen gas and blows away.

The top factors that affect denitrification speed are soil temperature and moisture. The cooler the soil, the less denitrification. The rule of thumb is that you should wait until soil temperatures go down to 10 C before applying nitrogen fertilizer. Like all rules of thumb, this is a rough guide – the biggest factor to consider is the weather. If you wait too long, you many not get all your fertilizer into the ground before freeze-up.  Even at low temperatures, denitrification can continue if soils are wet. With this fall’s dry conditions, it would take about 3 inches of rain to get to that point.

With anhydrous ammonia, the goal is to have the fertilizer overwinter as anhydrous before converting to nitrate for use by the crop. For granular fertilizer, there are products that delay the release of nitrogen and reduce the losses from denitrification, e.g. SuperU and ESN. So far these products are promising, however they do tend to be more expensive than the same amount of conventional fertilizer.

If you get a warm, wet spring where soil moisture and temperatures are high for a long time prior to seeding, you may lose your nitrogen fertilizer. At that point you may end up fertilizing your field twice with the expense and extra work that entails. Don’t fall apply to fields that are likely to be too wet to seed in early spring.

If you’re applying manure on your fields, these considerations also apply. To get the maximum return from the manure, it should be injected or worked into the soil as soon as possible to discourage denitrification.

Current regulations state that fall fertilizer application must be completed by November 10, so if it’s a long warm fall you may not be able to apply fertilizer in time.

By timing fall fertilizer application carefully, you can get the same yields as you get by applying the fertilizer in the spring and take advantage of more time, better prices, and a better seedbed.

With the large number of unseeded acres this year, many producers are considering hedging their bets for next spring by planting some winter wheat. Here are 8 tips for maximizing your winter wheat production.

1. Choose your field carefully. Seeding into spring wheat stubble is a bad choice as pests and diseases can carry over. If possible, use a field that was fallow or had oilseeds this summer. If you have to plant on a cereal field, choose a field that had barley or oats on it. A pre-seed application of glyphosate and something like Express Pro helps control perennial and biennial weeds that have crept into minimally tilled fields during wet years. A good stand of winter wheat often will choke out weeds.
2. Soil test. Soils are like a fuel tank without a gauge. A soil test tells you how much gas you’ve got and ensures you won’t run dry before the finish line. A growing season that’s swung between too wet and too dry plays havoc with soil nutrients levels.
3. Seed it right. Don’t just seed a fixed number of bushels per acre, instead use the germination, vigor, and estimated mortality of your seed batch to calculate the seeding rate for an ideal plant stand. The ideal plant stand for winter wheat is 30 plants per square foot. Make sure your seeder is calibrated correctly to ensure a uniform seed depth of about ½ to ¾ of an inch. To optimize winter survival, the field stubble needs to hold four inches or more of snow. If you are seeding into less than ideal stubble, you should increase your seeding rates as there will be more seed mortality.
4. Seed it at the right time. The most critical factor in getting a good winter wheat crop is the seeding date.  To qualify for crop insurance coverage winter wheat must be planted between August 20 to September 15. The crop should go into winter with 3-4 leaves, and perhaps one tiller. If the crop is acclimatized it can survive soil temperatures of –24oC early in the winter.
5. Supply the needed nitrogen. Winter wheat uses about 30-40% of its nitrogen by the 5-6 leaf. The current recommended practice for nitrogen is to broadcast it in the spring. However, advances in fertilizer coatings such as ESN (Environmentally Smart Nitrogen) allow you to put most of your nitrogen with the seed. This reduces the number of passes you have to make over a field, but it does cost more and you must be careful not to damage the fertilizer coating when applying it. Preliminary results from a study in Alberta suggest that seed row ESN did almost as well as spring broadcast urea or ammonium nitrate.
6. Provide phosphorous fertilizer with the seed. Winter wheat uses phosphorous twice; once when it germinates and establishes a crown in the fall, and again when it wakes up and starts to root from the crown in the spring.
7.  Consider potassium needs. Potassium might be required in sandy or organic soils. Potassium assists with winter hardness and crown development.
8. Choose the right variety. The key points to consider are days to maturity, height, stability, resistance to disease and relative winter hardiness. Pedigreed seed provides clean seed with a specified germination to ensure even stands.

Remember that to be successful you have to pay attention to the details!

Winning Winter Wheat

I recently attended a webinar on Managing Fusarium Head Blight Risk using WeatherFarm.

Key Principles for managing Fusarium Head Blight by Dr. Jeanie Gilbert of Cereal Research Centre (Plant pathologist for AAFC).

• 1993 was the most severe epidemic of FHB.
• The disease is driven by environmental conditions, so it varies a lot from year to year
• The pathogen is a fungus that exists in two states: vegetative and spore state.
• Primary transmission is via spores by air
• For an epedemic to occur need: susceptible host, spread of the pathogen, and a proper environment interaction
• Detrimental effects: Fusarium produces a mycotoxin, Reduces yields, Milling, baking, and pasta making properties altered, Reduced germination, Domestic and export markets suffer due to low tolerance of FHB damage
• Disease symptoms: wheat, oats, barley, corn (primary problem in corn is that it transmits to cereals)
• A lot of the most popular wheat varieties (76%) fall into the moderately susceptible to susceptible categories
• No-till seem to have have less FHB than minimum or conventional till.
• Rotation has an effect on on incidence, severity, and DON level
• Fungicides reduce FHB and DON compared to the control. Fungicides are more effective in more resistant varieties.
• Yields increased with each addition of a management strategy.

Using WeatherFarm’s online tool for FHB management decisions – Mike Grenier

• Requires an integrated management approach
• Crop rotation helps
• Fungicide use can reduce impact of FHB in epidemic years
• Goal of risk forecast is to assist in evaluating need for fungicides
• The frequency of epidemics varies regionally
• Variety – pathogen population – environment
• Relative Humidity, Temperature
• Updated forecasting model
• More weather stations / greater spatial density / real time reporting
• Still hard to measure pathogen presence in an area
• If you go to weatherfarm.com, there is a resource guide with lots of background information
• on weatherfarm you can zoom in and out to various areas and turn displays on and off
• The data supporting the mapping can be seen online
• The model is very good for the Red River Valley, good for western Manitoba, unsure of its accuracy in SK and AB – currently testing
• The key with fungicide is to monitor conditions during heading.
• Fungicide timing is key, but more of an art than a science
• By the time disease is evident, it’s too late for fungicide
• Management strategies focused on one strategy will likely fail under weather conditions favorable for FHB
• Rotation x Variety x Fungicide management
• Weather accounts for most of the yearly variation in FHB
• Future plans include risk forecast in next 24, 48, 721 hours

Alison – Other WeatherFarm site tools

• A big one I didn’t know about was live conditions.
• The hourly forecast is updated roughly every 6 hours
• The regional forecast and maps has a bunch of layers – temperatures, highs, lows, radar, etc.
• I use the historical information a lot
• Other maps on the site are growing Degree day maps, soil moisture maps, freeze severity, winter cereal survival
• Pest management maps
• temperature maps
• precipitation maps

In most cases, reseeding isn’t worth it, so why bother counting your plant stand?

First, it’s not too late to adjust the seeding rate on any late seeded fields. With what you’re seeing, you can adjust the seeding rate, depth, and speed to improve the plant populations in those fields.

Second, it gives you a target for next year. If you didn’t know that your plant stand was low, you won’t know why your yields are taking a hit. Next year you can look at making the necessary adjustments to improve your stand and give yourself a better start.

Speed can be a big factor in establishing a good plant stand. Going faster may cover more acres, but if you’re losing a lot of yield maybe it’s better to slow down. Uneven seeding depth can lead to a large variability in plant maturity (usually 1 day later in emergence in the spring means a couple days later in maturity in the fall), which will also knock down your yields. It’s a better return on investment to have 300 aces with maximum yields than 500 acres with poor yields.

Evaluating your plant stand is pretty simple. Start off with a lightweight hoop or square and determine its area using those formulas from geometry class. Next, walk into the field a bit and toss the hoop. Count the plants in the hoop. Repeat this six to eight times and take an average of your results. Divide this average by the area of the hoop to get the plants per square foot. This gives you your plant stand.

Each crop has an optimal plant stand. For my clients I aim at 8 plants per square foot for canola, 30 plants per square foot for wheat, and 150,000 plants per acre for soybeans at first trifoliate.

The Canola Council has shown that “a non-uniform stand can result in a 20% yield loss as compared to a uniform stand, even in a normal growing season. A uniform stand results in more even crop staging, making pesticide applications and swathing timing easier to stage.” It’s not just canola though, Bill May of AAFC has shown that the same considerations apply in cereals.

I haven’t personally done a full research trial but what I have seen is that as canola seed size gets larger, the seed vigor is better.

If your plant population is right up where it should be for optimal yields, congratulations! You’re well on your way to maximizing crop yield.

What can you do if your plant stand is low? Unless your stand is bad enough that you’re planning on filing a claim with MASC, reseeding or broadcasting additional seed is rarely worth it. Without the initial plant population there, your yields will be taking a hit but that doesn’t mean the situation is hopeless. With careful management and cooperative conditions, you can still pull off a good yield. The key at this point is to make sure that crop gets what it needs when it needs it. With a thinner crop stand, pesticide selection and timing is critical. You need to do everything you can to make sure that your plants survive and thrive to harvest time.

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Ron Tone has been an independent crop consultant in the St. Pierre area for the last fifteen years. He specializes in crop scouting, manure management, and crop damage claims. www.toneag.com / phone 204-433-7189