Machine harvesting for specialized processed and fresh markets

'Mini blues' in June 2017 putting on strong growth!
'Mini blues' in June 2017 putting on strong growth!
Our student crew harvests 'Legacy', August 2017
Our student crew harvests 'Legacy', August 2017
'Mini Blues' blanketed with snow, Januray 2017
'Mini Blues' blanketed with snow, Januray 2017
'Legacy' in the snow, January 2017
'Legacy' in the snow, January 2017
'Legacy' and 'Mini Blues' just planted, October 2015
'Legacy' and 'Mini Blues' just planted, October 2015

This study is being conducted at the NWREC in a 0.25 acre conventional planting of ‘Mini Blues’ and ‘Legacy’ established in 2015. The planting is designed for machine harvest.

Pruning treatments for ‘Mini Blues’ will start in the winter of 2017-18 (after the second growing season) – plants would then be old enough to start differential pruning. The pruning treatments that are proposed are based on a combination of Dr. Strik’s experience with this cultivar and what would be economical for growers including: 1) a conventional pruning method including bottom and top cuts to the bush [“control”]; 2) unpruned for at least 3 years [goal is to prune hard every few years]; 3) hand “speed” pruning in winter making only big cuts to base of bush; and 4) hedging immediately after last machine harvest in summer.

‘Legacy’ was pruned to have the first hand harvest in the second growing season (2017) and will be differentially pruned starting in the winter of 2017-18 using the following treatments: 1) standard pruning for 'Legacy' [B. Strik's grower recommendations]; 2) standard pruning for northern highbush; and 3) using a V-trellis with standard 'Legacy' pruning to encourage outward growth and open the center of the bush.

Data collected will include: tissue analysis (plant nutrient status) per treatment plot; soil analysis (combined/one per cultivar) – both used to adjust nutrient management programs during planting life; time required to prune per treatment (for economic comparisons); fresh pruning weights per treatment; machine-harvested yield (starting in 2018 for ‘Mini Blues’) and hand-harvested yield for ‘Legacy’ (2017) and hand plus machine harvested yield for ‘Legacy’ starting (from 2018 – onwards); average berry weight per harvest; a measurement of machine-harvest efficiency (collection of fruit on the ground and calculated as a percentage of total yield lost to ground).

Winter 2017/18 Update:

This was the first cropping year for ‘Legacy’. Plants were hand harvested three times, on July 12, 19, and 27. Average yield was 2.3 lb/plant (1.67 tons/acre) with an average berry weight of 2.1 g (weighted by percent of yield at each harvest). We did have some bird pressure in this plot that reduced yield and will be better managed going forward into the main cropping years. ‘Mini Blues’ was pruned to remove all fruit in winter 2016-17 (average of 16.13 hours/acre for pruning).

A composite leaf sample from all plots (separated by cultivar) was taken in late July and a composite soil sample was collected in late Oct/early Nov. Leaf nutrient levels were within the normal range expected for young plants, which can be different than mature plants (i.e. lower leaf N in young plants).

Both ‘Legacy’ and ‘Mini Blues’ plants continued to show strong growth during the 2017 season and are on track for pruning treatments and machine harvest in 2018 (with the first one to two harvests of ‘Legacy’ by hand). While this is earlier than is recommended for many cultivars/plantings as plants are generally too small with weaker crowns/roots at this age (and can be rocked out of the ground during harvest, based on our experience), we feel that these varieties can be managed this way. In our opinion, this would lead to an economical machine-harvest only production system for ‘Mini Blues’ and a combination of hand- and machine-harvest system for ‘Legacy’.