Cold weather is increasing the risk of frost damage to sugarbeet, with increasing cases of damage being reported. Freezing temperatures followed by sudden thaws could cause the deterioration of roots.
Crops in clamps are likely to be most susceptible to frost damage. Maus clamps with a higher surface area may be more prone. Crops still in the ground may be at lower risk but this will depend on the extent of insulation provided by canopy leaf growth. Gappy crops and those affected by foliar disease or beet moth (where is less leaf cover to protect them) will also be more susceptible.
Beet tends to freeze at temperatures below minus 3 degrees C and below. However, the susceptibility to frost damage will be highly variable from field to field and even between plants within a field. Sources of variation may be different air temperatures and duration of low temperatures, acclimation due to prior cold exposure and stress history of the crop, and of course the extent of top leaf cover. The chart below highlights how the severity of damage increases with duration and intensity of freezing temperatures.
Fig 1: Damage increases due to severity and length of cold period.
- Recent temperatures will have increased the risk of frost damage, but in many fields, conditions will have been borderline for more extensive damage.
- Some harvesters are unable to harvest as the ground is just too hard. Where the ground is frozen and has not thawed in the day, there may be no symptoms showing. Cold conditions appear to be set for the week with some warmer temperatures at the weekend when we will see a greater thaw and the extent of any damage will become more visible.
- It may be worth checking crops. Check the crown of the beet to see if it is frozen. Digging and then slicing some roots into sections, and them letting them thaw for a few hours should reveal the extent of damage.
Symptoms of frost damage will be apparent when beets have thawed following freezing. Damage will be more apparent from the crown down through the root and will depend on the extent of freezing. Damage is due to rupturing of the cells. On thawing, a frosted root will take on a translucent glassy appearance with the vascular rings more prominent and may have a brown/black discoloration. Frost damage may be followed by secondary rots caused by fungi and bacteria, this will be more severe the warmer the temperatures are following frost damage.
However, not all frosted beets will deteriorate, and in some cases, beets will stabilise but may have a lower sugar content and higher impurity level.
Assessing Levels Of Frost Damage - as temperatures are forecast to remain low for the rest of the week, it will take a while for any symptoms to show fully. Organise a programme of checks across roadside piles, any longer-term clamps, and crops in the ground to get a complete picture as possible. Keep checking for symptom progression when temperatures increase.
Reduce Risk Of Frost Damage - whilst the risk of frost remains, focus on clearing roadside stock rather than increasing harvested crops, as beets will be more protected in the ground. Make sure any longer-term clamps have level tops to avoid frost pockets from forming, and ideally consider covering clamps, if possible. Do not load frosted beets into longer-term storage clamps.
If the crop shows signs of deterioration, you may want to consider lowering scalpers to remove more of the crown. Careful consideration must be taken to ensure there is a net benefit to crop yield and not an excessive loss of sound roots. Also, skim clamps to remove deteriorated beet before delivery.
Communications - keep in close contact with your harvester operator, haulier and your British Sugar Account Manager on any potential issues.