by Peter Burgess
Wild blueberry production involves a unique cropping system: wild stands are grown on a two-year cycle and harvested in a single pass. The vast majority of the crop goes directly to processing.
Historically, post-harvest handling was not a priority as the quality was preserved by cleaning and freezing the berries within 24 hours after harvest.
However, as competition with worldwide highbush blueberry production increases and industry margins tighten, minimizing the loss of fruit and maximizing fruit quality from the harvester to the freezer plant is becoming more important.
Having a higher proportion of high-grade fruit make it through the processing line increases the value of the end product. This should help the entire production chain – for both the farmer and the processor. However, farmers don’t often closely consider their harvest and post-harvest practices and how they could directly impact the fruit and their bottom line before the fruit even gets to the scale.
Bruised and cut fruit obviously impacts overall quality, but also reduces the weight in the tote. Damaged fruit will leak, and gross weight will decrease all the way from the harvester to the scale. This can mean a direct loss in revenue for the farmer. So, what can farmers do to minimize loss and preserve fruit quality?
Weeds have probably the biggest impact on fruit quality. Any grower who has driven a harvester through heavy Hair fescue knows the impact it can have on the fruit. Besides reducing yield through competition, a large portion of the crop doesn’t make it to the tote, and the fruit that does is often wet and damaged. Keeping weed populations in check is critical for maintaining fruit quality.
Properly maintained and optimally run harvesters make a huge difference in fruit quality. As an example, Dr. Travis Esau at Dalhousie’s Agricultural Campus has shown that brushes on harvester heads need to be adjusted regularly to keep the heads free of debris. A dirty head picks less fruit, and that fruit can be damaged. The harvester operator can also drastically impact fruit quality by overfilling totes. The extra weight in a tote can easily lead to crushed fruit.
Weather conditions at harvest can also impact fruit quality. As the temperature rises, ripe fruit becomes softer. Midday temperatures above 25 degrees Celsius can lead to increased bruising and damage to fruit. Most fresh pack operations see a decrease in fruit quality when berries are picked in hot conditions. Similarly, if harvested fruit stays in the field for a long period, fruit quality and weight will decrease.
All fruit respires once it has been harvested and the respiration rate increases with temperature. A tote of berries harvested at 8 a.m. will weigh less 12 hours later, particularly in warm conditions. It is critical to rapidly move harvested fruit out of the sun and to the processing facility to preserve quality.
Conversely, harvesting in wet conditions will also result in poor fruit quality. Besides leading to more debris in the bin, picking when plants are wet will lead to more debris staying in the teeth of the harvester head. When there is debris in the head, the fruit is more likely to be damaged.
Finally, once the berries are harvested, transporting them to a receiving station can have a major impact on fruit quality. Driving loaders fast across a field or driving trailers quickly over rough roads can dramatically shake the berries and bruise the fruit. Wild blueberries are a soft fruit and should be treated with care.
When some of these factors are combined, particularly late in the season when the fruit is fully ripe, juice can run out of the tote before it leaves the field.
Consider these things to minimize losses when planning a harvest season: keep weeds under control, keep a well-maintained harvester, avoid picking in wet or extremely hot conditions whenever possible, don’t overfill the totes, try to move harvested fruit to the receiving shed and out of the sun, and treat the harvested fruit with care, for instance driving loaders and trucks slowly when transporting fruit.
(Peter Burgess is a wild blueberry specialist with Perennia Food and Agriculture Inc. based in Bible Hill, N.S. He works closely with the wild blueberry industry in Nova Scotia to assist producers with production, pest identification, pest controls, and whole system management issues.)