Producers learn more about effective carrot storage

During his presentation, Vikram Bisht reminded his audience that, “The storability of carrots is greatly influenced by the in-season practices and handling of carrots prior to storage … To have the best product for our customers, it is quite important that we bring in healthy, disease-free material.”

By Tamara Botting

When carrots are harvested, it may be months before they reach the consumers.

To help Canadian farmers have the best final product and the least amount of avoidable loss, Fruit and Vegetable magazine presented the Fresh from the Field: Post-Harvest Best Practices for Carrots and Potatoes webinar for producers in November 2025, sponsored by Wyma Solutions.

Vikram Bisht, Potato and Horticulture Crops Pathologist with Manitoba Agriculture, was one of the presenters.

His portion of the presentation focused on the best post-harvest practices for carrots, and as he noted right away, “The storability of carrots is greatly influenced by the in-season practices and handling of carrots prior to storage … To have the best product for our customers, it is quite important that we bring in healthy, disease-free material. For that, we need well-drained soils; balanced fertility; good disease, insect and weed control.”

One of the big dangers to carrots while they’re still in the field is Sclerotinia disease, which can lead to severe rotting if preventative measures aren’t taken.

Bisht noted that in Manitoba, some producers have reported losing nearly half of their product in storage due to this rot. That’s why both in-field and post-harvest management is essential.

He suggested trimming the foliage between rows to improve airflow and to keep the under canopy dry, noting that this can help reduce the risk of infection of the carrots.

Bisht said there aren’t many in-field chemical options available for carrots when it comes to fungicides. While Switch 62.5 WG and Button (Cyprodinil+Fludioxonil) were effective against Botrytis grey mold and Sclerotinia white mold, there’s a limit of a maximum of two sprays in the field per season. Allegro 500F or Vantana (Fluazinam) are recommended at no more than three sequential applications.

If the disease pressure in a particular year is high, Bisht said it might be helpful to have a post-harvest treatment with the fungicide Scholar (Fludioxonil), which is registered for a dipping or drench treatment. The efficacy of the spray vs. drench treatments will be impacted by the amount of soil or mud on the carrots; it is most effective on washed carrots, but not all carrots are washed prior to storage.

Of course, that’s another question that carrot producers have to consider when they’re harvesting their crop: to wash or not to wash? There are advantages and disadvantages for each option.

Bisht stressed the importance of not harvesting carrots when it’s hot, and also to of cooling carrots down quickly when they’re brought in from the field, calling it a “critical thing to do.”

Washing the carrots means hydro-cooling them, which is a lot faster and more efficient than using forced air cooling. With forced air cooling, you’d need to be in the range of 1,000 to 3,000 cubic feet per minute (CFM)/ ton.) However, there are fewer risks of spreading pathogens when you leave the carrots unwashed until just before shipping. Moreover, soil has beneficial microbes, which are left intact to compete with harmful pathogens when the carrots are left unwashed.

Washing the carrots when they’re harvested eliminates a step when they’re being processed for shipment later – before they go out, they’ll need to be washed at some point, disinfected and packaged into breathable bags or cartons for shipping.

Since shipping often happens in the wintertime, if the washing area isn’t heated, holding off on washing until later can mean an unpleasant experience for those doing the work.

At the same time, when the carrots are being washed, there’s a greater chance that they’ll be damaged during the process, and physical injuries to carrots can create entry points for rot pathogens, meaning that delaying washing can mean a better product for consumers.

Ultimately, each producer will have to determine what the best approach is for their own operation.

Bisht did offer some broad suggestions that are good for any producer to keep in mind as they harvest, so that they can have the best possible outcome:

• Reduce mechanical damage as much as possible when handling the carrots during harvest, so as to not create entry points for rot pathogens

• Monitor and manage the temperature and relative humidity of your carrot storage facility well

• Apply a post-harvest fungicide (again, being aware that the efficacy of this will be determined by how much soil is on the carrots, if washing is being done later)

• Trim the greens on the carrots, otherwise they’ll draw the moisture out of the carrots and make them rubbery or flaccid

• Carrots should never be stored near ethylene-producing fruits, such as apples and pears, as the gas can cause a bitter flavour in carrots.

When carrots are being put into storage for a while, it’s common for them to be put in large wooden or plastic boxes or containers. If that’s the case, there should be gaps between the container stacks, so air can freely circulate through the bottom of the stacks and escape through the top.

If the carrots are being stored in bulk on the floor, then there needs to be aeration pipes on the ground. Air circulation prevents buildup of condensation or hot spots.

Either way, “Air flow is extremely important. Stale air can lead to condensation on the carrots and create anaerobic conditions, and that would lead to soft rot issues,” Bisht said.

He added that high-capacity fans and ducts should be configured to move cold air through the storage space and extract metabolic heat and gases. Control systems help ensure uniform conditions throughout the storage space.

The ideal storage temperature for carrots is near 0 to 1 degree C (32 to 34 degrees F). Once that temperature is achieved, the airflow should be at 5 to 10 CFM/ ton.

Carrot storages also should have a relative humidity level of 95 percent-plus.

Bisht said it’s common for humidification systems for carrots to use an ultra-fine fog that is non-wetting. This allows there to be adequate moisture in the air, which prevents the carrots from dehydrating.

He noted that there are some companies in Canada that offer equipment rentals to help with managing things like temperature, relative humidity and airflow, and that without a good refrigeration system, it would be almost impossible to hold carrots for over six to nine months.

It’s not just about checking gauges, though – Bisht recommended actually going into the storage space fairly regularly and searching for signs of spoilage, whether by look or smell, and removing them immediately.

Inadequate storage can cause losses for carrot producers in several ways, most commonly:

• Weight loss, due to drying out or mould infestation

• Quality deterioration, due to humidity and temperature differences

• Waste of energy, due to inefficient cooling and ventilation

• Risk of spoilage and losses in bulk storage (diseases include Sclerotinia and soft rot)

However, taking steps to make sure your storage is operating properly will help to reduce or even eliminate these kinds of losses. 