Frost 2020

One of the toughest things cranberry growers do is managing springtime frost conditions. In the spring, there is a danger to the crop when the temperature drops. Typically, a cranberry bog is built at a lower level than the land immediately surrounding it and the bog temperature can drop ten to fifteen degrees lower than the uplands. These conditions make monitoring bog temperature a top priority once the winter water comes off. It’s no exaggeration to say there would be no crop if we didn’t watch for frost on the bogs.

The first step is monitoring the temperature. Each bog has a thermometer (usually located in the coldest section) that requires frequent checking throughout the first part of the night. Once the temperature drops to between 33 and 35 degrees Fahrenheit (depending on the stage of growth), it’s time to turn on the pumps. More than forty years ago we used to flood the bogs to prevent frost damage; we now use sprinklers instead. When the water from the sprinklers freezes on the vines, it controls the temperature well enough to keep them from harm. It’s also necessary to check the surrounding reservoirs and canals to make sure that the water supply is sufficient to supply the pumps. That can take some time, and doesn’t always need to be done all at once. Depending on location and conditions–is the bog surrounded by woods? Where is the wind coming from? Is the sky clear or overcast?–some will be started earlier than others.

“We’ve had five frost nights so far this year,” says manager Matt Giberson. “Last week was the coldest; we hit 22 degrees in a few places and I believe it would have hit 19 or so if we hadn’t started the pumps. We had reflooded a lot of the bogs that we took off in the last week and a half, so we only had about fifteen to twenty pumps to run, which helps.” Although no one on the team is a huge fan of frost, the weather is perfect and exactly how they want it for now. “Being so cold the last two weeks, nothing is moving, which is helping us be more flexible with the number of systems we need to get in,” Matt says. “The sprinkler crews have been doing a great job in hitting the target every day, getting in at least five systems a day. They’ve been doing so well, in fact, that if we get enough in during the week we have the time to take a day and just go back to clean and do repairs. Another benefit of being so cold is even the plants that are still under water aren’t moving. This helps because some years, if it gets really warm in April, as soon as you take off the water you have to start frost protecting. This year allows us thus far to take our time to take water off slowly and get pumps ready in a timely manner.”

water moving to the next bog

In recent years we’ve moved to an automation process to make this easier on our team, with a combination of automated and analog thermometers for optimal monitoring. The automated thermometer gives us the initial indication that the temperature is dropping. When it hits the first threshold, it sends the notification, and that’s when members of the frost team would head out to look at the analog thermometers. This year, we’ve taken that a step further to further increase our efficiency and lower our fuel costs.


“We programmed 4 pumps to turn on when the temperature in the beds they cover went below a certain level, and then off when the temp got up to the level we wanted,” says COO Bryan vonHahmann. There have been some minor challenges but nothing the team can’t handle: “2 systems dipped below and came on no problem, and also shut off when temp rose beyond our desired level. With the other two, the thermometers were reading just above the low level so they didn’t come on. We waited 20 minutes and they still didn’t dip below; we were anxious so we turned them on manually. That’s when we learned that if we turn them on manually, they wont shut off automatically when they rise above the upper limit. We have another procedure now if that is the case. Ultimately we will let them come on when the thermometers tell them to, and it won’t be an issue.” They also had some settings mysteriously change from the start of the run to the end, so are trying to figure that out and monitoring it closely. “We need to do more programming to create a mesh of thermometers that will turn a pump on instead of relying on just one or two.”

The program may still have a few bugs, but the team feels confident that things are headed in the right direction!

Water drawdown – 2020

Spring has arrived and it’s time to start removing the winter flood! We’ve said it so often you can probably recite it with us by now: good water management is absolutely critical to growing cranberries. Growers rely on a clean, abundant supply to maintain the bogs year round. The key question, as everyone here knows by heart, is “Where is the water coming from, and where do you want it to go?”

Once the harvest is over, the bogs are flooded in order to protect the cranberry vines from the winter weather. When the warmer weather sets in, the bogs are drained so that the dormant vines awaken for the growing season; while cranberries are most frequently harvested using the “wet pick” method, they do not actually grow under water and thus need to go through the same growing cycle as any other fruit crop. The process, which we call “dumping water” is deceptively simple: a team member takes a gate hook (pictured below) and removes the boards that have been placed across the gate in the bog. (The boards are removed in a specific pattern to work with gravity and the natural flow of the water.) Once the boards have been pulled and placed on top of the gate, the water moves to the next bog along the ditches. This water returns to the reservoirs and canals in order to be reused for the next part of the cycle. It takes about 24 hours to drain completely.

After the water comes off, a crew will install sprinklers (if they haven’t been installed already) and makes sure the irrigation systems are 100% by turning on the system and letting it run for a while. Then they’ll clean out the nozzles, see where we need to make repairs, and turn the system back on to make sure the repairs worked.

Running the system for a bit also helps the team make sure that any potential engine problems are taken care of by the Facilities/Equipment team. It’s important for this to be done as soon as possible for frost protection. Typically, a cranberry bog is built at a lower level than the land immediately surrounding it and the bog temperature can drop ten to fifteen degrees lower than the uplands. These conditions make monitoring bog temperature a top priority once the winter water comes off, which is why installing sprinklers quickly and efficiently is so important.

“Things are a little different this year with COVID-19,” says manager Matt Giberson. “We had a late start, so we focused on putting systems in and re-flooding. One, to help with frost nights, and two, because a few of the guys on the frost team are delayed due to virus precautions. We usually get five to six systems done in a day but because we were delayed, our team worked late and was able to get eight to thirteen systems in a day to get us back on track. So we’ve been doing a lot more taking off water and putting it back on. We have plenty of water and wells; now we just need to get everything re-flooded within a few days.”

Once it’s all done, everything should be on track for the cold nights still to come!

Frost

One of the toughest things cranberry growers do is managing springtime frost conditions. In the spring, there is a danger to the crop when the temperature drops. Typically, a cranberry bog is built at a lower level than the land immediately surrounding it and the bog temperature can drop ten to fifteen degrees lower than the uplands. These conditions make monitoring bog temperature a top priority once the winter water comes off. It’s no exaggeration to say there would be no crop if we didn’t watch for frost on the bogs. A night riding along with Jeremy Fenstermaker is an exercise in watching the weather, the water . . . and managing sleep patterns.

The call by our general manager usually goes out in the early evening; depending on the forecast, the frost team can go out anywhere from 9 P.M. to 1 A.M. This particular evening, we started at 9. The guys each have their own section to run: Jeremy’s is located on Sim Place. The night begins with making sure we have everything we need: boots, warm clothing, head lamps, and coffee (especially coffee!). And then we’re off for a long night in the middle of the bogs.

The first step is monitoring the temperature. Each bog has a thermometer (usually located in the coldest section) that requires frequent checking throughout the first part of the night.

Once the temperature drops to between 33 and 35 degrees Fahrenheit (depending on the stage of growth), it’s time to turn on the pumps. On these particular systems, the pumps need to be running at about 45 psi. More than forty years ago we used to flood the bogs to prevent frost damage; we now use sprinklers instead. When the water from the sprinklers freezes on the vines, it controls the temperature well enough to keep them from harm.


It’s also necessary to check the surrounding reservoirs and canals to make sure that the water supply is sufficient to supply the pumps.


That can take some time, and doesn’t always need to be done all at once. Depending on location and conditions–is the bog surrounded by woods? Where is the wind coming from? Is the sky clear or overcast?–some will be started earlier than others. Once they’re all started, though, the work isn’t over. The next thing is making sure all the sprinklers are working correctly. This means driving around with a spotlight and checking to make sure they’re running at full capacity.

It may sometimes be necessary to repair the sprinklers, as they won’t run at full capacity if something is blocking the line. This happens more frequently when the systems first start running, and becomes less of an issue after a few cold nights.

This goes on for the rest of the night. It does get a little easier when the sun comes up, simply because the light is better.

Once the sun comes up and we’re done the repairs, it’s time to start checking the temperature to see if it’s safe to turn off the pumps. Once the thermometer reads around 35 degrees or so and the ice is breaking up, we’re okay to shut down.

After the pumps are shut down and the paperwork is turned in, it’s off to get some sleep!