3. On the farm
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3.1. Before the harvest
The farmer or producer, by growing the crop in the first place, has already primed the need for a marketing process. The conditions under which the crop are grown, the cultural practices used, the variety of crop grown and when it was planted, will all determine:
You cannot improve the quality of any fresh produce after harvest. Thus the ultimate market quality of the produce is determined by the grower from the moment he selects the crop, the variety and the production system.
From an economic standpoint, you cannot grow fresh produce without various capital inputs for the purchase of seed, fertilizer and pesticides, Considerable time and labour is spent on land preparation, cultivation, irrigation, crop protection and eventually on the harvest of the produce. All of these inputs must be balanced by a good return from the marketing process, and the only way this can be achieved is by careful planning and management of all aspects of production.
3.1.1. Production Planning
The Gospel of production planning has been, and continues to be preached by all and sundry in the Eastern Caribbean region. Nevertheless, we are still seeing gluts and deficits in produce and farmers incomes depressed as a result. Most of the farmers in the region have only small production areas, often on scattered lots which are difficult to get to, difficult to work and highly prone to erosion. Under these circumstances, there is clearly little or no scope for mechanization and an immediate limitation placed on the crops that can be successfully grown at a profit (this does not of course preclude crops grown for subsistence).
Yield is a worthy objective and it makes obvious sense to get the most out of your land with each crop, but when every farmer grows the same crop at the same time, high yield is an embarrassment with no market and a tremendous loss economically. Financial yield per acre, or hectare, is and should always be the register of success in production.
Production planning means a lot more than Just selecting the crop and variety to be planted. It means planning:
Failure to include crop marketing requirements as part of production planning can result in crop failure and poor quality for several reasons:
3.1.2. Crop Selection
The selection of the type of crop will be governed by several inter-related factors. If a grower has no previous experience of a crop he would be foolish to plant more than a few plants on which to experiment. If there is no domestic market for a particular crop for traditional reasons, and the grower has no facilities for export, again there is no point in growing that crop except for experimental or subsistence purposes.
The grower's soil and fertility will be deciding factors. For example, carrots and sweet potatoes give a higher yield with fewer post-harvest problems if grown on lighter soils that have not received heavy manuring immediately prior to planting whereas bananas require rich fertile loamy soils that have good water absorption properties but which drain freely.
Vegetable crops occupy land space for relatively short periods, but tree-crops are a more permanent investment and it may be a question of years rather than weeks or months before the first harvest of fruit is obtained. This can present a serious cash-flow problem for the grower with limited credit facilities. Inter-cropping with annual vegetables or fast-growing crops may alleviate the cash flow problem e.g. planting papaw or hot pepper between rows of slower growing young citrus trees.
Seasonal conditions are probably one of the major deciding factors influencing crop selection. Many vegetable crops grow better with fewer pest and disease problems in the dry season provided they have adequate water and overcast skies do not shut out too much sunlight. However, with careful management these same crops may also be grown at other times of the year, and although capital inputs may be greater, this may be balanced by better market prices. (e.g. St. Kitts early potato production).
3.1.3. Varietal Selection
Varietal selection is frequently made on the basis of yield potential, disease resistance, or suitability for local conditions, and often without sufficient consideration of market preferences and post-harvest behaviour. Seed availability of the correct variety is still a very limiting factor in the Eastern Caribbean. For cash cropping purposes, the selection of the variety should follow a clear order of priorities:
Crops grown from poor, stale or diseased seeds or planting material rarely thrive and the resulting produce will be of poor quality.
3.1.4. Production Practices
Production practices require as much planning as other factors because they often involve capital and labour costs, but more importantly because they influence the production quality of the produce and thus the potential post-harvest life and marketability of the crop.
Irrigation increases crop turgidity at harvest but depending on commodity, stage of maturity and other factors, may make the crop more susceptible to bruising and splitting. Over-irrigation and under-irrigation are a double-edged sword and either can reduce yield, quality and marketability of the crop.
Over-irrigation of cucumbers and melons increases fruit size but leads to greater losses due to decay, both before and after harvest, and reduces the intensity of the fruit flavour. Under-irrigation of the same crop improves fruit flavour, but yields are reduced and growth cracks are common. Over-irrigation of leafy vegetables prior to harvest may increase their turgidity but will also make the leaves more brittle and susceptible to handling damage.
Un-irrigated grapefruit grown under dry conditions will have a low Juice content and develop a thicker peel. The low Juice content of grapefruit may mean a delay in harvesting due to lack of irrigation and this leads to reduced storage life of the fruit, but also greater rejection rates at harvest because of field blemishes. Conversely, harvesting of all types of citrus immediately after irrigation, when the peel cells are fully turgid, increases the incidence of oil spotting, and prevents their export to extra-regional markets.
Crops growing in competition with weeds may suffer from both water stress and mineral deficiency leading to lower yields and quality. Weeds may also harbour pests and diseases which attack the crop, detract from its appearance and increase the incidence of postharvest spoilage. Failure to prune out Jagged, dead wood in citrus trees makes harvesting difficult, harbours decay organisms and causes physical injury to the fruit, both before and during harvesting. Such damage and latent disease infection are major causes of quality downgrading and storage losses in citrus and many other tree fruits. Lack of careful land preparation and maintenance of channels in furrow irrigation of crops may cause one end of the crop furrow to be over-irrigated and the other end under-irrigated.
Soil fertility has a direct effect on all aspects of crop growth and development. In some cases, post-harvest disorders can be linked directly to the deficiency of a particular mineral, but often other environmental factors such as water stress are involved. "Spongy tissue" symptoms in mango have been linked to mineral deficiency, and copper and iron deficiencies cause abnormal peel development in citrus fruits.
In general, fruits and vegetables growing under low fertility conditions are slow to mature, have a greater tendency to develop abnormal shape, do not store well, and ripen irregularly after harvest.
FERTILISER - YOU ONLY GET OUT OF A CROP WHAT YOU PUT IN!
All chemicals applied to growing fruits and vegetables have an effect on quality, and in some cases are applied specifically for their effect on post-harvest behaviour.
Chemicals applied to fruit and vegetable crops are of two types:
- Pesticides -- including insecticides, fungicides, and nematicides, are applied primarily to protect the crop and should therefore improve its quality potential. Their effect is also to reduce insect and fungal damage which detracts from the appearance of the crop and increases storage losses. In some cases, for example the development of 'Anthracnose' spotting in mango, it is necessary to spray with fungicide during growth even though the disease itself may not be seen until after harvest. By removing weed competition, which may impose water stress and mineral stress, herbicides can also have beneficial effects on postharvest behaviour.
Since all crop protection chemicals are toxic to animals and humans, they must be applied in concentrations which will not allow toxic residues to build-up. A safe period specified by the manufacturers must be left between final application and harvest. Produce exported to developed countries is rejected if tests reveal pesticide residues above the permitted level.
Careless application of herbicide between rows of crops, and spray mists blown over from neighbouring fields, can cause irreversible damage to a growing crop, usually in the form of external blemishes and discolourations which reduce market value. Severe damage by herbicides may lead to gross deformities of the produce and possibly total crop loss.
Pesticides are of little use in combating bacterial wilt diseases (e.g. 'Moko' disease in banana) and virus infection. The only solution in these cases is removal and burning of the infected plants and possibly sterilization of surrounding soil. (With Moko disease, the herbicide glyphosate ('Roundup') is used to kill all host plant tissue and not to 'kill' the disease!)
- Growth regulators -- have a widespread use on fruit crops, causing physiological changes which will improve marketability. For example, "Ethrel", an ethylene releasing compound may be applied to pineapples just before harvest to stimulate uniform ripening. "Gibrel", a gibberellin formulation is sprayed on citrus orchards to delay flowering and thus extend the harvest season. However, the use of growth regulator chemicals is not straightforward, and incorrect application may either give no effect (and be a waste of money) or a harmful effect, e.g. "Ethrel" can increase acidity and cause excessive softening of pineapple if incorrectly applied.
3.1.5. Maturity for Harvest
Much research has been carried out on determining the correct stage for harvesting a crop. Reliable technical tests have been developed for important commercial crops such as citrus and pineapples grown on a large scale under more or less uniform conditions. These tests are, however, mostly dependent on laboratory and field tests requiring costly equipment and technical skills which are out of the reach of small scale growers with limited resources.
In the Caribbean where multiple cropping on small acreages accounts for a large proportion of fresh produce production, decisions on when to harvest are not made on technical test but on the individual's evaluation of when the crop is in good enough condition to be harvested, and sold to realise the best price.
A major factor influencing this decision is the price which can be obtained at any given time, which frequently leads to crops being harvested before or after they are at their best in order to get a good price. This practice is not confined to the Caribbean, or indeed to less developed countries.
HOW DO WE KNOW WHEN A CROP IS READY FOR HARVEST?
Two characteristics are normally used in deciding crop maturity, both very dependent on the experience and personal opinion of the grower.
Observation, or looking for characteristic signs of readiness such as:
Sampling of characteristic specimens and testing by:
Some crops, such as cabbage and yam, are acceptable for consumption over a wide range of development and selection for harvest is often more dependent upon price and the size preferences of the market.
Other crops, as seen in Figure 3.1 (see Figure 3.1. Commercial maturity for different fresh produce) below, must be harvested at a specific maturity or they will be unmarketable for reasons such as poor flavour, high fibre content, and/or rapid postharvest deterioration.
Pineapple for local consumption and for canning is generally harvested at around the 2530% yellowing stage of the fruit, whereas fruit for export may be either totally green or more normally just showing the first signs of yellowing at the basal end. Mango harvest criteria can vary with local consumption patterns and distance to the market. Time from flowering combined with fullness of mango cheeks are the commonest criteria.
Producers must decide whether to harvest as soon as the market price ensures a reasonable return, or to leave the crop in the field to obtain maximum yield. However, waiting too long for yield increase may drastically shorten the marketable life of the produce and lower the sale price. This balance is a critical factor in determining the growers income from the crop. In practice the total harvest period is very short and the grower has very little time in which to make the correct decision.
With vegetable field crops such as green beans, okra and tomato, the harvest once begun, must be continuous in order to pick produce at the same stage of maturity to give a consistent supply to the market.
3.2. Managing the harvest
3.2.1. Harvesting Objectives
The objective is to harvest the crop without damage and to get it to the market in the best possible condition. Although the scale of production, availability of labour and type of produce may vary, certain basic factors must be taken into account in the planning of any harvest operation. Equipment must be obtained, labour organized, and marketable produce identified for harvesting, collection and removal from the field. Each of these tasks must be planned, managed and implemented efficiently if the value of the crop is to be fully realised.
Harvest management has four components:
- to move the crop from field to buyer with the minimum number of handling operations compatible with the quality requirements of the buyer;
- to minimise exposure of the crop to stresses such as extremes of temperature, or of compression pressures caused by over-loading. If harvested clean, the produce should be kept clean and not stacked on the soil, even momentarily.
Good management of the harvest operations is usually reflected in the speed at which produce moves from field to market place, packing station or storage centre, provided that is not at the expense of careful handling and subsequent quality downgrading
Training and supervision of labour are critical to a successful harvesting operation. Constant supervision is necessary to maintain quality and reduce subsequent spoilage of produce. Training is required in both general principles and crop specific techniques relating to maturity selection, detachment method maintenance of equipment, field hygiene and division of labour. Some of the more important areas are:
Teams of workers must work systematically through a plot or field, experienced staff removing the crop and others carrying it to collection points. If crops are relatively inaccessible, as with older mango, avocado and breadfruit trees, great care must be taken by pickers climbing in the trees if fruit is to be harvested free of damage. Whenever possible, planting densities and pruning techniques should be chose which minimise tree size.
It is essential that crops are harvested at the correct size and maturity for the market. The workers must be given strict specifications before entering the field and each worker's performance carefully supervised.
Careful instructions must be given on the correct method of cutting, twisting or pulling to remove a crop, and the performance of each worker checked.
During long harvesting sessions, some individuals develop habits of slapping, pressing and rubbing produce. Others become tired and start to throw or drop produce into field containers. Such practices can cause damage to the produce and should be controlled by checking performance, by restricting the lengths of shifts worked, and by promoting comfortable working conditions.
Sharp edges on rings and bracelets, and long fingernails, are significant cause of postharvest abrasions and should be removed before harvesting starts.
Unmarketable produce must not be left in the field to rot and contaminate healthy standing crops. Routine collection of waste is an important part of the harvesting operation, and all workers can contribute to this. Cleaning, sterilization or replacement of picking containers must be carried out regularly to prevent the build-up of infection.
Each individual should be issued once only with necessary equipment and given clear instruction and training in its maintenance. It should then become that individual's responsibility to keep knives and clippers both clean and sharp, and to keep other equipment such as boxes, poles, nets and bags in a good state of repair. Blunt and dirty knives and clippers are potent sources of bacterial soft-rot contamination of both fruits and vegetables.
3.2.3. Harvest Maturity
Optimum commercial harvest maturity of fruits and vegetables is covered in Section 3.1.5. of this manual as an essential preharvest consideration. However, it is just as important that the state of maturity is maintained throughout the harvest period. Failure to do so will lead to inconsistency of produce quality and to lowered market prices.
3.2.4. Time of Harvesting
The time of day at which to harvest will depend on the availability of transport and other facilities, weather and environmental conditions and human factors, as well as market demands and quotas. The factor which assumes greatest importance depends upon the crop and the local situation.
3.2.5. Harvesting Techniques
The method will vary according to the types of commodity described to be harvested. Additional information on specific commodities can be found in the Appendix to this manual.
(i) Root and tubers - like sweet potatoes, yams, cassava and ginger, may be completely buried in the soil, or may be partly visible above the soil surface, as in dasheen, carrots and turnip. Those which develop below soil level, if they are small, are best grown in mounds or raised beds, so that a digging tool can be easily pushed underneath to lift them when they can be freed from the soil without damage. (see Figure 3.2. Harvesting root crops with a fork).
Dasheens, carrots and other partly buried crops can also be lifted in this way or, if soil conditions are right, be pulled by hand.
Larger roots or tubers, such as some types of yams and cassava, are harvested by carefully scraping away the soil from above and around them by hand.
Tools used to lift root crops are a matter of personal choice and/or tradition. As shown in Figure 3.3. (see Figure 3.3. Harvesting tools for root crops) below, they include: digging sticks, cutlasses (machetes), hoes or digging forks. Always use sharp instruments with great care so as not to wound or cut the produce because this will give rise to rapid spoilage by soil-borne pathogens.
(ii) Leafy vegetables. bulbs and flowers - These will include leafy vegetables like callaloo and spinach in which individual leaves are picked by hand, or lettuce and cabbage where the main stalk is cut through with a sharp knife. Cauliflowers are also harvested by cutting the main stalk of the plant, but with broccoli the flowering shoots are usually broken off by hand and then trimmed with a sharp knife if necessary.
Bulbs, such as mature bulb onions and garlic are usually harvested like root crops, by pushing a digging tool under them and levering them up to free the roots from the soil, or again, they may sometimes be pulled by hand.
Tools used are, the hands, sharp knives or digging tools. When knives are used they must be kept sharp, clean and free from soil, or they may contaminate cut surfaces and cause bacterial soft rot.
The cut or broken ends of stems should NEVER BE PLACED IN DIRECT CONTACT WITH THE SOIL, NOR PLACED IN CONTAINERS CONTAMINATED WITH DIRT OR DECAYING PLANT MATERIAL.
(iii) Fruits --Harvesting methods for fruits are variable and depend to some extent upon whether they are immature, mature green or ripe when harvested:
- Mature or ripe fruits with natural stem 'break points'
Some fruit, such as passion fruit and tomatoes have a natural 'break-point' at which they can easily be removed from the parent plant, leaving the fruit stalk attached to the fruit. These are usually harvested by hand using the 'lift, twist or pull method', (see Figure 3.4. Harvesting tomato by the lift and twist method). Passion fruit, however, may be left on the vine until fully ripe and harvested by shaking the trellis on which they grow, causing ripe fruit to fall to the ground, from where they are gathered. They suffer little or no damage due to the hardness of the outer "shell".
- Mature green or ripe fruit not readily detached with the fruit stalk intact
Many tree fruits fall into this category, including mango, citrus and avocado. These fruits are best harvested using clippers, and placed in harvesting bags carried by the harvester. Figure 3.5. (see Figure 3.5. Harvesting aids and tools for tree fruits) illustrates various aids and tools for harvesting tree fruits.
With large trees, such as mature mangoes and avocadoes, fruits are harvested by the use of picking poles, with or without attached clippers, equipped with bags into which the fruit fall. This method is rather slow and requires considerable experience and skill, but is essential if high quality fruit is required.
Alternatively the fruit is picked by the harvester either on a ladder, or who climbs the trees, and throws the fruit to a skilled 'catcher' on the ground, or into a large net. (A good method for breadfruit!). Pulling out of stems from fruit when harvesting has to be avoided at all costs because broken skin at the point of attachment of the stem is particularly susceptible to a decay condition know as STEM END ROT.
- Immature fruit with soft stems but no natural breakpoint
Many fruits are eaten in the immature state, some as vegetables or salads. They include sweet peppers, papayas, cucumbers, okras, eggplant and christophene (chocho).
Fruits of this type are usually harvested by hand by snapping the stem, or cutting it with a sharp knife. Where knives are used they should be kept sharp and free from contamination with soil.
Breaking off the stem instead of cutting is not recommended because the rough break is more susceptible to the establishment of infection by decay organism than a clean cut.
Immature green legume pods such as green beans and peas have a short fruit stalk which can usually be easily broken away from the plant.
NO MATTER WHAT HARVESTING METHOD IS USED CARE MUST BE TAKEN TO AVOID INJURY TO PRODUCE.
3.3. Getting produce ready for market
Once produce is harvested it should be prepared, sorted and assembled together for transport to the market, packhouse or storage area as soon as possible. This stage of getting the produce ready for the market should be thoroughly planned, as with all aspects of fresh produce production and marketing.
3.3.1. Preparing and Sorting in the Field
Much of the required preparation and sorting of produce can be done during the harvest operation itself. Scarred, pitted, over-ripe or otherwise deficient produce can be placed in separate harvest containers or discarded completely and removed from the field later. More rigorous preparation such as washing and critical size or ripeness/colouration selection may be better performed in a packhouse, as described in Section 5.2. of this manual. However, for most of the crops harvested in the Eastern Caribbean the requirements are generally only for simple sorting and packing in the field, or assembly of the produce prior to collection and transport.
There is a growing tendency towards the practice of packing produce directly into final marketing containers in the field, reducing the number of times the produce is handled with a corresponding reduction in the amount of injury caused. This practice however requires that appropriate selection and packaging facilities are set up for the purpose, together with adequate supervision.
Whatever the process, assembly of the produce is always necessary, and like putting all your eggs in one basket, it is often the point when troubles or problems first arise.
As with all aspects of post-harvest, the objective of assembly should be to develop a system which minimises stress on the produce and keeps handling operations to a minimum but with maximum care and to keep the time between harvest and first destination of the produce as brief as possible.
Clearly, reaching such an objective does not happen by accident, but only by carefully planning the assembly process as carefully as all other operations are planned.
3.3.2. Field Assembly
What do we mean by ASSEMBLY?
An aggregation and bringing together of like commodities for the purpose of transport and/or wholesale marketing.
Unless field plots are very small, it will be necessary to assemble the harvested crop in preparation for transport. Interruptions in the harvesting operation due to rain or other reasons, can and will occur.
Field assembly should be planned bearing in mind the best location and the provision of basic facilities.
3.3.3. Field Crates and Containers
Harvested produce may be transferred from the harvest containers into field containers, for transport to a packing house, or in some cases for transport direct to local markets.
3.3.4. Transport Out of the Field
To get the produce from harvest point to a collection point by the roadside may involve passing over one or more kilometers of farm roads. Growers rarely give sufficient attention to the logistics of this operation and then wonder why they get problems. In the Eastern Caribbean, this problem is compounded by the topography. In many cases 'heading-out' or mule are the only alternatives and crates may not be as suitable as sacks.
If you can get a vehicle in close to the field it should not be overloaded (as is often seen with banana pick-ups) and it should have good suspension and with preferably larger wheels and lower tyre pressures to take out some of the jolts.
VEHICLES SHOULD BE DRIVEN SLOWLY!
Packing between vehicles and crates with soft straw or leaves can help cushion the blow but make sure it is clean. Why infect healthy produce with dirty packing material?
DO NOT RIDE ON TOP OF THE PRODUCE!
Is the vehicle shaded from both sun and rain? If the produce is covered with a protective tarpaulin or similar, does it prevent ventilation of the produce?
Often the above points are overlooked because the operators argue that the produce does not have far to travel and the produce is not expected to be on the vehicle for long. Unfortunately, drivers do have the habit of making unscheduled stops during their journeys. They may stop for lunch on the way, or to speak to their friends/girlfriends, and often the fact that the pick-up is parked in the full sun is forgotten.
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