Jun 9, 2021

Industry innovates to find best ways to grow fruit

(This is another in a series of stories marking the 60th anniversary of Fruit Growers News).

The tree fruit industry reached a full maturation point over the course of the 20th century.

Jerome Hull Jr. of Michigan State University wrote a July 1997 article for The Great Lakes Fruit Growers News that reflected on the evolution of the sector over the years prior to that time. The following is an excerpt from that report.

An amazing amount of research and technology has been developed and adopted by the fruit industry since World War II. These remarkable changes resulted from amazing discoveries, new technology and grower initiative.

Sulfur, copper, lime sulfur, lead arsenate, spray lime (for softening lead arsenate) and nicotine sulfate were supplanted by organic pesticides following World War II. These new pesticides resulted in more successful disease and insect control and were also less phytotoxic to the foliage. As a result of improved insect control and less chemical injury to the foliage, trees became much more productive and yields per acre nearly doubled.

The transition in pesticides, fungicides with longer periods of eradicative action, pesticides absorbed and translocated within the foliage in the tree, and changes in formulation have continued to make insect and disease control more easily and effectively accomplished.

These changes did not occur without some associated problems. Mites became a problem following the introduction of organic pesticides. New pests appeared as improved control of primary pests was achieved. Pesticide resistance became another concern in the continuing battle growers wage with the demons of nature.

Fruit finish was another challenge in the pesticide transition. The concerns about copper and sulfur injury on both fruit and foliage were supplanted by the effect of climate and formulation of some of the organic pesticides on fruit finish. Solvents in some emulsifiable concentrates caused russet development and some wetable powders produced scarf-skin, russet and surface blemishes. Low temperatures in early spring were also associated with these problems.

Pest control evolves

Integrated management of pest control during the past 25 year has been greatly facilitated by research. This includes, (1) improved understanding of the biology and life cycles of any of our pests, (2) isolation and manufacture of pheromones to help monitor pests, (3) improved climatic gathering equipment to fairly accurately forecast, predict or determine likelihood of insect or disease infection, development emergence or presence and need for protection or eradication.

Changes in pesticides have been accompanied by dynamic changes in applicator equipment. Dusters, hydraulic spray masts mounted on a spray tank were succeeded by air blast sprayers. These air delivery systems carried the spray droplets into the tree canopy and more rapidly deposited pesticides throughout the tree canopy. These sprayers required changes in pruning practices to (1) open the canopy for satisfactory spray distribution and (2) lower tree height to effectively cover the top of the canopy.

Concentrate spraying required less water to spray an area and reduced application time. It was followed by air shear nozzles, droplet generators and low volume spraying.

Orchards are often on elevated or sloping sites for air drainage and less susceptibility to frost. To prevent serious soil erosion and provide traffic support for equipment, a sod cover is maintained. This vegetation aroundthe tree can be very competitive with trees for moisture and nutrients. Cultivation was practiced to control vegetation around the trees or in the tree row to minimize this competition. This was achieved with a disk or rotary tree hoe, but damage to tree roots near the soil surface and occasional damage to tree trunks was common.

Mulching was another effective control, but was expensive and provided a haven for mice. 2,4 D was one of the first organic herbicides available following World War II to very effectively control a number of broad-leaved weeds. Today, herbicides control vegetation in the tree row, resulting in improved tree growth and yields, but some tolerant and resistant weed species and noxious perennials now challenge many orchardists.

The rotary mower, developed to more rapidly mow airport runways, was soon adopted by orchardists to mow grass in the orchard allyway faster than the sickle bar mower.

Growth regulators kick in

Growth regulators significantly changed our industry. Chemical thinning helped overcome biennial bearing and significantly increased annual production. Stop drop chemical controlled pre-harvest crop loss. Other chemicals have been developed to
affect fruit shape maturity and finish, as well as control vegetative growth and promote floral initiation.

Orchard nutrition has undergone remarkable changes. The introduction of leaf analysis aided in the identification of nutrient deficiencies and providing recommendations of fertilizer applications to more accurately meet the needs of the tree.

Long ladders were required to harvest fruit from tall trees. Pickers often bruised fruit in the bottom of the picking bucket as the bottom of the picking bucket hit each ladder rung as they descended the ladder. Large trees, often 25 feet in height or taller, required long ladders that fatigued harvesters during the day, resulting in less efficiency during the later part of the day and more bruising.

Handling bushel crates required considerable manpower. Introduction of the fork lift, and pallets (later bulk bins) probably never saved growers money, but certainly avoided many back strains and sore muscles, and reduced fruit bruising and handling operations. Bulk bins required bin dumpers that have been succeeded by water dumpsters to more gently handle the fruit during the grading and packing. Washing and waxing enhanced fruit appearance.

Predicting and determining fruit maturity progressed from assessment of coloration, seed color and ease of separation and days from bloom to harvest prediction models based on temperatures following bloom to measurements of internal ethylene and flesh starch changes. Storage scald and bitter pit research provided practices for control or prevention.

(Next month: More of Jerry Hull’s documentation of the tree fruit industry’s evolution in the 20th century.)

— Gary Pullano, editor