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Published May 17, 2008, 12:00 AM

Will's Windmill Column: Sprayer pressure gauges must be accurate

There are many things that affect the end result (efficacy) from a pesticide application.

By: by Will Yliniemi, University of Minnesota Extension Service, DL-Online

There are many things that affect the end result (efficacy) from a pesticide application. The most obvious ones are: careful scouting (knowing exactly what the problem is); selecting the best pesticide to take care of the problem; applying the right amount of pesticide per acre uniformly on the target; keeping as much of the pesticide applied as possible in the intended area of application; weather conditions during the application; and timing of application.

Other than the weather conditions, you can control all the other factors mentioned above. So, how do we achieve conditions that help us keep the pesticide applied in the application area with maximum deposit on the target? The answer is in the size of the droplets.

In general, smaller droplets are more effective, especially for insecticide and fungicide applications. However, small droplets are highly susceptible to spray drift, increasing the risk of losing them. Nozzles not only help us achieve a precise flow rate and the desired spray pattern, they also are a key factor in droplet size.

Pressure gauges on sprayers are there for one reason: measure the actual pressure. They are important accessories of a spraying system because pressure affects both the amount of liquid being sprayed and droplet size. A malfunctioning pressure gauge may result in over or under application of pesticides, and significant changes in droplet size.

Increasing pressure causes an increase in the number of small droplets, and in the flow rate. Decreasing pressure does the opposite, increasing of droplet size and reducing flow rate. For instance, increasing the pressure by a factor of 4 doubles the flow rate.

To accurately regulate spray pressure, it first has to be measured. Use a pressure gauge with a range at least twice the expected operating pressure. A pulsation damper protects and increases the life of a pressure gauge and smoothes pressure pulsations, which makes reading the gauge much easier.

There is usually a pressure drop in the spray line between where the pressure regulator valve is located and the nozzles. Therefore, pressure gauges should be located as close to the nozzles as possible, and the pressures at the nozzles should be checked at least once to determine the magnitude of the pressure drop.

Having an accurate pressure gauge is essential to proper calibration of a sprayer. Therefore, compare the readings from your pressure gauge periodically with the readings from another calibrated gauge.

For more information on pressure gauges, talk to your plant protection chemical equipment dealer, or contact me, Will Yliniemi, Hubbard/Becker County Extension educator, by phone at 1-218-732-3391 or 1-218-846-7328, by cell at 1-218-252-1042, or by e-mail at ylini003@umn.edu. Source: Ohio State Extension C.O.R.N. Newsletter.

Surviving winter

Did you ever wonder how many of our wildlife animals are able to survive our harsh winters, such as the one we just experienced in northern Minnesota? What special adaptations do they have that keeps them warm and alive during those cold winter months?

Winter is a challenging time for Minnesota’s wildlife. The days are shorter and the nights are longer. There is snow covering the ground hiding away sources of food. Finally, the temperature can get below freezing and cold winds can steal away body heat very quickly.

So how do animals stay warm enough to survive these harsh conditions? For all the “warm-blooded” critters out there, it is vital to keep warm in order to maintain their bodies at a constant temperature. If they cannot do this, they will die. Birds and mammals fall into this category.

Birds employ multiple strategies to keep warm such as fluffing their feathers, huddling together, and shivering. A very successful way to cope with winter is simply to go to a warmer place, which is what many bird species are doing when they migrate.

Mammals, while they don’t have feathers to keep them warm, have fur that usually becomes thicker in the months approaching winter. Just like feathers on a bird, fur insulates the body by trapping air that is warmed by the animal’s body heat. Smaller animals such as mice and voles can remain active the entire winter, looking for food in a network of tunnels under the snow. Air becomes trapped between snowflakes, and is warmed by animals creating an “igloo-like” environment.

Those mammals that do not remain active may hibernate, a condition in which breathing, heartbeat, and body temperature is lowered to conserve energy. Examples of animals that hibernate are groundhogs and many species of bats.

For those critters that are cold-blooded, meaning their body temperature changes with that of their surroundings, remaining active during winter isn’t likely. Snakes, lizards, frogs, toads, and salamanders will slow down their body processes almost to a stop during winter. This strategy is known as diapause. When these animals are in diapause, they use a small amount of stored energy in the form of body fat to keep themselves barely alive until temperatures rise. These critters “sleep” the winter away in logs, rock piles, compost heaps, and any other place where they are safe from predators.

Ever wonder why you can see flies buzzing around on a warm January day, and then as soon as the temperature falls the next day, the flies disappear? That is because many insects over-winter in a dormant state, called quiescence. They will remain inactive until the temperature in their microhabitat (i.e. a log) warms enough to support physiological processes. A warm day in February could “waken” insects only for them to become dormant again when temperatures cool.

As you can see, the natural world has all sorts of adaptation features, which help animals survive our harsh winters. It is quite amazing!

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