Tag Archives: spring 2019

Frost – 2019

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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.

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 head out to look at the analog thermometers.

Holding the winter flood until later in the month means that we’ve not had many frost night yet, says Gerardo Ortiz. “We went out one night this week around 3 A.M. It hasn’t been too bad. There’s a chance Saturday night and definitely Sunday is going to be one of the coldest night we’ve had. It’s going to be an early night and a long one, I think. We’ll see how it goes!”

Water drawdown – 2019

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Spring is here for good, which means 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.

“We had a lot of water this year and the reservoirs were really high,” says Matt Giberson. “So we decided to do an early draw on some systems, put the sprinklers in, and then re-flooded so we could prevent running frost early as well as focus on some other tasks, particularly the latest renovations. We’re slowly taking it all off now for good and will be finished by late next week or early the following week.”

That early draw does present some challenges, especially with repairs, since you can’t repair sprinklers when they’re underwater. 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. “The team in charge of repairs will need to do a little more now that all the water is coming off after the early draw, but we have plenty of guys available for that; it all works out!” Matt says.

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.

Once it’s all done, everything should be on track for the cold nights coming up!