Stephanie Walker

A Systems Approach to Chile Harvest Mechanization

There is approximately a half century of published research on harvest mechanization of cultivars of Capsicum annuum var. annuum L. This review focuses primarily on research pertaining to chile for canning and fresh markets. Most of the crop is still harvested by hand, displacing production to locations where labor costs are low. Mechanizing chile harvest will require a systems approach, integrating research in plant breeding, production practices, and harvester and processing plant machinery design. Cultivars need to be selected for high determinant fruit set, low attachment force, and increased fruit wall toughness. Production practices need to be modified to cause the development of tall, well-rooted plants with minimal branching. Harvest machinery needs to be developed that is both aggressive enough to remove almost all fruit and gentle enough to minimize damage. Processing plant equipment needs to be developed to handle fruit that may have more foreign matter, some stems still attached, and will arrive in large batches. A fully mechanized harvest will not be possible until each part of the system is in place.

Green Chile Pepper Harvest Mechanization

High cost and unavailability of labor for hand harvest has resulted in domestic chile production declining even as consumption grows. Mechanization is necessary but has resisted four decades of diligent research effort. Five picking mechanisms were tested in five cultivars in two fields in New Mexico in 2008. Harvest efficiency was 42% to 90%, with 11% to 45% mechanical damage for a net collection of marketable peppers that ranged from 28% to 80% of total yield. An inclined counter-rotating open-helix design with a clear product path had the highest harvest efficiency and lowest percentage of product damage. Cultivar response to mechanical harvest provided feedback for the New Mexico State University chile breeding program.

Comparative Mechanical Harvest Efficiency of Six New Mexico Pod–type Green Chile Pepper Cultivars

New mexico pod–type green chile (Capsicum annuum) is one of New Mexico’s leading horticultural commodities. Cultivated acreage of green chile in NewMexico is threatened because of the high cost and insufficiently available labor for hand harvest. Therefore, mechanization is necessary to sustain the industry. Successful mechanization depends on harvester design coupled with plant architecture that optimizes harvest yield and quality. Harvested green fruit must be whole, unbroken, and unblemished for fresh and processedmarkets, so harvester design and plant architecture must maximize yield while minimizing fruit damage. In two trials conducted at the New Mexico State University Agricultural Science Center in Los Lunas, six cultivars (AZ-1904, Machete, PHB-205, E9, PDJ.7, and RK3-35) were evaluated for plant architecture and harvest efficiency with a double, open-helix mechanical harvester with two counter-rotating heads. Cultivars were direct seeded on 17 Apr. 2015 and 14 Apr. 2016 and managed according to standard production practices. Plant architecture traits, plant width, plant height, height to first primary branch, distance between first primary branch and first node, basal stem diameter, and number of basal branches were measured before harvest. Mechanical harvest yield components, which included marketable fruit, broken fruit, ground fall losses, unharvested fruit remaining on branches, and nonpod plant material, were assessed after once-over destructive harvests on 2 Sept. 2015 and 31 Aug. 2016. Fruit width, fruit length, and pericarp thickness were measured from a representative sample of 10 marketable fruit. In 2015, ‘AZ-1904’ and ‘PDJ.7’ had significantly (P £ 0.05) more marketable yield than ‘Machete’ that had the least marketable yield. No statistically significant differences were found in marketable yield in 2016. When both years were combined, ‘PDJ.7’ had significantly more nonpod plant material harvested and the plants were taller than all other cultivars. We found mechanical harvest performance to be significantly affected by plant height, with shorter plants yielding less marketable fruit. Despite differences in fruit wall thickness, no significant differences were measured in broken fruit. In 2015, ‘AZ-1904’ had significantly less basal branches per plant, reducing obstruction for the picking mechanism. Harvest efficiencies (marketable harvested fruit yield as a percentage of total plot yields) ranged from 64.6% to 39.3% during this 2-year trial, with the highest harvesting cultivars PDJ.7 and AZ-1904. In the future, all new mexico pod–type green chile breeding efforts for mechanical harvest must incorporate desirable plant architecture traits to increase harvest efficiencies.

Rubber Finger Stripper Harvester for Green Chile

Harvest mechanization as a system requires modifying or creating new components including cultivars, production practices, and harvest, transportation and processing plant machinery. New Mexican chile is one of the last segments of the pepper industry to still rely on hand labor. This paper reports on an experimental field harvester for succulent NM chile. Rubber fingers on a variable speed chain drive strip fruit from the plant and convey it to field cleaning sections of an existing pepper harvester. Field trials in 2010 showed moderate damage (12% of total yield) but harvest efficiency (56% of total plot yield) still leaves room for improvement. Part of that improvement may be realized through cultural practices that minimize branching and improve resistance to uprooting.