Handbook of Vanilla Science and Technology

The other cultivation system existing in Costa Rica is the intensive vanilla cultivation (Figure 3.3). The pioneers of this system were the foreign investors who implemented an intensive vanilla cultivation under shade netting. The number of vanilla plants per hectare is from 2,000 to 6,000. However, if the plant density is too high, the vanilla plants will not flower or the blooms will be scarce. The more plants per hectare, the lower the yield per hectare. The main density of the plant biomass should have good light exposure, with good air circulation and good drainage. There should be enough space between beds and plants to allow the vanilla plant to fully grow. A growth of 15 m per year, for 5 years, depending of the cultural practices and organic matter used, is to be expected. Since it is an intensive system, it needs more hand labor for weeding, guiding of the stem, and pollination than in a traditional system.

Fig. 3.3 Intensive vanilla production system.

The infrastructure is another difference between a traditional and an intensive system. The initial investment in the construction of net house beds and tutors is expensive, as is the maintenance of these structures for more than 7 years. Because of these high costs in the initial construction, the materials must be of high quality to last more than 7 years, or at least up to the first harvest. The net house post, wires, and tutors must be chosen well, otherwise structure maintenance will be expensive. Another difference of an intensive system is the irrigation system. It must have an irrigation system in the summer period to avoid the fall of the vanilla beans and stressing of the vanilla plant.

3.5 PROPAGATION

There are several vanilla cultivars and species cultivated in Costa Rica. The common vanilla species used are V. planifolia, V. tahitensis, V. pompona, and native species from Costa Rica. As discussed in Section 3.2.3, a common cultivar used is “Vaitsy”, although the proper species designation is not known. These different vanillas have different physiological and morphological characteristics, such as vanillin content, bean size, stem thickness, and disease resistance (Table 3.1).

Table 3.1 Vanilla cultivar differences

Characteristics |“Vaitsy” | V. planifolia | V. tahitensis

Stem thickness, inches | 4 | 2 | 1

Flower size | Large | Medium | Small

Bean size, cm | From 16 to 27 | From 16 to 20 | From 13 to 18

Growth rate, m per year | 10 | 5 | 15

Water stress resistance | Medium | Low | High

Fusarium resistance | Medium | Low | High

Anthracnose resistance | High | Medium | Low

There are two propagation methods for vanilla plants in Costa Rica. The conventional way is to take a stem cutting of the vanilla plant 1 m long and put it in a planting medium. Placing a stem node under the medium in a dark and moist location promotes root growth. This vegetative vanilla propagation method has the advantage that in 3 years the vanilla plant could be blooming. This method reduces, from 1 to 2 years, the time before harvest compared to the in vitro method. If there is not enough vegetative material for planting, or if there is the need to decontaminate the plantation from a disease, then tissue culture is a good option. The tissue culture method, where small plantlets are produced from a mother plant, is done in private laboratories. In Costa Rica there are three private laboratories that generate tissue-culture derived vanilla plants. The plantlets are given to the vanilla farmer when they reach 3 cm in length (Figure 3.4). Before planting, these plantlets must first be acclimatized in a separate area provided with 80% shade until they are strong enough to endure rain, sun, pests, and diseases (Figure 3.4). This is a very sensitive stage where significant plant losses were reported in other countries (Chin 2004). The medium used for acclimatization is very important in the reduction of plant losses. The medium usually used is peat moss, rice hulls, or ornamental red stone. After 15 days, the small plants are fertilized and a bactericide can be applied. After 3 months, the plants are ready for planting inside the net house or in the open field. Around 80% survival of acclimatized vanilla plants was reported in some farms in Costa Rica. It can take about 4 to 5 years for the plants to bloom. Since the young plant is soft and succulent, it is more attractive to pests such as crickets and worms and some other insects. The most common disease is Erwinia xansatinova at this young stage.

Fig. 3.4 Tissue culture derived vanilla plantlets.

3.6 DISEASES AND PESTS