The quality and condition of produce sent to market and its subsequent selling price are directly affected by the care taken during harvesting and field handling. Whatever the scale of operations or the resources of labour and equipment available, the planning and carrying out of harvesting operations must observe basic principles.

Objectives

The objective of the grower should be:

to harvest a good quality crop in good condition;
to keep the harvested produce in good condition until it is consumed or sold;
to dispose of the crop to a buyer or through a market as soon as possible after harvest.

Planning

To meet these objectives, success in harvesting and marketing must depend on planning from the earliest stages of production, particularly in regard to:

Crop selection and timing to meet expected market requirements;
Contacts with buyers so that the crop can be sold at a good price when ready for harvest;
Planning harvest operations in good time; arranging for labour, equipment and transport;
Providing full supervision at all stages of harvesting and field handling.

Labour

With small-scale family production for local markets, the labour supply will probably not be a problem. As the scale of commercial production and the distances between the rural producer and urban consumer increase, more exacting requirements will have to be met in regard to training and supervising labour. It is economically sound in terms of return to invest more in proper packing and handling of the produce before it leaves the farm. Growers will have to train their own field labour, accepting whatever support local extension workers are able to provide.

Training workers. This training should cover general aspects of produce-handling for all workers and specific training for those engaged in tasks requiring greater skill.

General training. For everyone concerned with harvesting and field handling, general training should include:

Demonstrations of the causes and effects of damage to produce, emphasising the need for careful handling at all times to avoid mechanical injuries from such causes as:

Wooden containers with rough edges, splinters, protruding nails or staples;
Overpacking containers which are to be stacked;
Damaging produce with long fingernails or jewellery;
Dropping or throwing into containers at a distance;
Throwing, dropping or rough handling of field containers.

An explanation of the need to avoid the contamination of harvested produce from such causes as:

Placing the produce directly on to the soil, especially wet soil;
Using dirty harvesting or field containers contaminated with soil, crop residues or decaying produce: containers must be kept clean;
Contact with oil, gasoline, or any chemicals other than those used specifically for authorised post-harvest treatments.

Workers allocated to specialised tasks, such as crop selection and harvesting, and the post-harvest selection, grading and packing (if applicable) of the crop should be given specific training. This will include demonstration and explanation of:

The methods of evaluating the readiness of the crop for harvest, and the rejection of unsuitable produce at harvest, according to market requirements;
The actual technique to be employed in harvesting produce, e.g. breaking the stem or plucking, clipping, cutting or digging;
The use of harvest containers, and the transfer of produce to field or marketing containers;
The selection of marketable produce at the field assembly point and (if applicable) grading for size and quality;
The correct application of post-harvest treatment (where produce is to be packed on the farm directly into marketing packages), e.g. fungicides, wax coating;
The method of packing market packages or other containers.

When are conditions right for harvesting a crop?

When the crop is ready for harvest, labour and transport are available, and operations organised, the decision as to when to start harvesting will depend largely on:

Weather conditions
The state of the market

The flexibility of the marketing date will depend on the crops. Some, such as root crops, can be harvested and sold over a long period, or stored on the farm to await favourable prices. Others, such as soft berry fruits, must be marketed as soon as they are ready or they will spoil.

When the decision to harvest has been made, the best time of day must be considered. The aim is to dispatch the produce to market in the best possible condition, that is, as cool as possible, properly packed and free from damage.

The basic rules to observe are:

Harvest during the coolest part of the day: early morning or late afternoon;
Do not harvest produce when it is wet from dew or rain. Wet produce will overheat if not well ventilated, and it will be more likely to decay. Some produce may be more subject to damage when wet, e.g. oil spotting and rind breakdown in some citrus fruits;
Protect harvested produce in the field by putting it under open-sided shade when transport is not immediately available. Produce left exposed to direct sunlight will get very hot. For example, eggplant and potatoes left exposed to tropical sunlight for four hours can reach temperatures of almost 50 degrees Celsius.

Produce for local markets can be harvested early in the morning. For more distant markets it may be an advantage-if suitable transport can be arranged to harvest in the late afternoon and transport to market at night or early the next morning.

Harvesting technique

By hand. In developing countries, most produce for internal rural and urban markets is harvested by hand. Larger commercial producers may find a degree of mechanisation an advantage, but the use of sophisticated harvesting machinery will be limited for the most part to agro-industrial production of cash crops for processing or export or both. In most circumstances, harvesting by hand, if done properly, will result in less damage to produce than will machine-harvesting.

Hand-harvesting is usual where fruit or other produce is at various stages of maturity within the crop, that is, where there is a need for repeated visits to harvest the crop over a period of time. Machine-harvesting is usually viable only when an entire crop is harvested at one time.

Root and tuber crops. Most staple roots and tubers that grow beneath the soil are likely to suffer a mechanical injury at harvest because of digging tools, which may be wooden sticks, machetes (or cutlasses, pangas or bolos), hoes or forks.

Harvesting of these crops is easier if they are grown on raised beds or mounds, or "earthed up" as is common in potato-growing. This enables the digging tool to be pushed into the soil under the roots or tubers, which then can be levered upwards, loosening the soil and decreasing the possibility of damage to the crop.

Other root crops, such as taro, carrots, turnips, radishes, etc. can be loosened from the soil in a similar manner by inserting the tool into the soil at an angle and levering the roots upwards. This method can also be used for celery if it has been earthed up or buried to blanch the stems.

Vegetables. Either the whole or a part of vegetative growth can be harvested by hands only or sharp knives. Knives must be kept sharp and clean at all times or they may spread virus diseases from plant to plant. Harvesting methods vary with plant parts harvested:

Leaves only (spinach, etc.) and lateral buds (Brussels sprouts): the stem is snapped off by hand;
The above-ground part of the plant (cabbage, lettuce): the main stem is cut through with a heavy knife, and trimming is done in the field (the cut stem must not be placed on the soil);
Bulbs (green onions, leeks, mature bulb onions): immature green onions can usually be pulled from the soil by hand; leeks, garlic and mature bulb onions are loosened by using a digging fork as for root crops (such as carrots) and lifted by hand. Simple tractor implements are available for undermining bulbs and bringing them to the surface.

Flower structures. Immature flower heads (cauliflower, broccoli) can be cut with a sharp knife and trimmed in the field; broccoli can be snapped off by hand and subsequently trimmed;

Mature flowers (squash, pumpkin): flowers are plucked individually by hand, or whole shoot-bearing flowers are harvested as a vegetable.

Fruits. Many ripe fruits and some immature seed-bearing structures such as legume pods have a natural break-point of the fruit stalk, which can easily be broken at harvest. Fruit and other seed-bearing structures harvested in the immature or unripe green state are more difficult to pick without causing damage to either the produce or the plant. These are best harvested by cutting them from the plant, using clippers, secateurs or sharp knives. The clippers may be mounted on long poles for tree fruits, with a bag attached to the pole to catch the fruit.

Plucking methods vary according to the kind of produce being harvested:

Ripe fruits with a natural break-point, which leaves the stalk attached to the fruit, are best removed by a "lift, twist and pull" series of movements, e.g. apple, passion fruit, tomato;
Mature green or ripe fruits with woody stalks which break at the junction of the fruit and the stalk are best clipped from the tree, leaving up to a centimetre of fruit stalk attached. If the stems are broken off at the fruit itself. Disease may enter the stem scar and give rise to stem-end rot, e.g. mango, citrus, avocado;
Immature fruits with fleshy stems can be cut with a sharp knife, e.g. zucchini, okra, papaya, capsicum; these can also be harvested by breaking the stem by hand, but this method may damage the plant or fruit and the rough break will be more susceptible to decay than would a clean cut.

Mechanical aids. Because the supply of fresh produce to domestic markets in developing countries comes mainly from relatively small-scale producers with limited resources, mechanical systems for "once over" crop harvesting are likely to be rare. There is scope, however, for the use of mechanical aids in modest commercial operations, especially where tractors are available.

The jobs where such aids are likely to be of use are:

In harvesting potatoes, onions and possibly some other root crops, simple tractor-drawn harvesters to lift up the crops and leave them on the soil surface;
In transporting produce from the harvesting point to the assembly area to await transport, tractors to draw trailers of laden containers or to carry either containers on pallets or bins.

Harvesting and field containers

The packing of produce directly into marketing packages in the field at harvest reduces the damage caused by multiple handling and is used increasingly by commercial growers. It is not a common practice in rural areas, where produce is sent to nearby markets and elaborate packaging cannot be justified, but commercial growers can view it as cost-effective if the packaging takes produce in better condition to market, where it can command a higher price.

At all stages of harvesting and handling, methods should aim at avoiding damage to produce and providing ventilation to prevent temperature rises.

Selecting field containers for harvesting. These must be of a size that can be conveniently carried by the harvest worker while moving through the field:

Harvesting bags with shoulder or waist slings can be used for fruits with firm skins like citrus and avocados. They are easy to carry and leave both hands free. They should be designed for opening at the base to allow produce to be emptied through the bottom into a field container without tipping the bag;
Plastic buckets or other containers are suitable for harvesting fruits that are more easily crushed, such as tomatoes. The containers should be smooth, with no sharp edges or projections to damage the produce;
Baskets are often used for harvesting but may have sharp edges or splinters that can injure produce. If they are not sturdy, they may bend out of shape when lifted or tipped-especially if they are large-and crush or otherwise damage the contents;
Bulk bins, usually of 250 to 500 kg capacity, are used by commercial growers, where crops such as apples or cabbages are sent to large-scale packing houses for selection, grading and packing. Bins can be carried by a fork-lift attachment on a tractor to move the produce from harvesting points to assembly areas.

When unventilated bulk bins are used in the field, produce should be left in them only briefly, and protected from sun or rain. Produce held in bulk for long will overheat and be more subject to decay. Bulk bins transported over long distances must be perforated to minimise heat build-up in the contents.

Post-harvest hauling

Field and farm transport. Routes for the movement of fresh produce within farm fields should be planned before crops are planted. Farm roads should be kept in good condition because great damage can be inflicted on produce carried over rough roads in unsuitable vehicles.

Containers must be loaded on vehicles carefully and stacked in such a way that they cannot shift or collapse, damaging their contents. Vehicles need good shock absorbers and low-pressure tyres and must move with care. Jolting of laden containers can aggravate damage to produce on rough roads, even at low vehicle speeds.

Transport from the farm. The destination of fresh produce leaving the farm will usually be one of the following:

A local market - produce is usually in small containers carried sometimes by animals or in animal-drawn carts, but mostly by vehicles owned or hired by growers; public transport is sometimes used.
A commercial packing house or processing plant-produce carried by trucks may be in palletised field containers, in bulk bins or in hand-loaded sacks or wooden or plastic boxes; where vehicles wait in the sun or rain for long periods before unloading, only the top part of the load should be protected by a covering; grass or leaves are not recommended for this purpose because they restrict ventilation and may be a source of disease; complete enclosing of the load with a tarpaulin is disastrous because it restricts ventilation and the temperature of the produce rises rapidly.
A city market - this applies only where produce is packed in marketing containers on the farm; the conditions under which these should be carried are discussed in the section on transport.

Harvesting and Field Handling