FIGURE 22.1 Vanilla cultivation system, in “acahual.”
DIVERSIFIED CITRUS GROVES
The extensive amount of Citrus cultivation in coastal Veracruz has allowed farmers to use these plantings as support trees (Figure 22.2). Most groves consist of Valencia oranges, which have excellent characteristics as vanilla support trees, for example, strong branches that grow laterally and that can permit a large quantity of vanilla vines. The Citrus trees also provide semifiltered sunlight throughout the year, which encourages vigorous growth and flowering usually in the second year after planting. Ventilation is considered good, resulting in less problems with pathogens and more vegetative growth than is typical of “acahual” systems. Compared to more intensive systems of vanilla cultivation, vanilla grown in Citrus groves entails a reduced cost of production since there is no investment required for support trees.
FIGURE 22.2 Vanilla cultivation system in Citrus groves.
Each proprietor owns between 1 and 5 ha, which obtain yields that fluctuate from 0.5 to 3.0 tons of green vanilla/ha.
INTENSIVE (MONOCULTURE)
This system is characterized by the use of nitrogen-fixing legumes (Erythrina sp. and Gliricidia sp.) as support trees and planting densities of between 1000 and 5000 support trees/ha. This density allows for some of the highest yields of any system, although generally such a success is obtained in only one year (the fourth or fifth year following planting). After a bumper season, yields in this system often decline drastically because of overcrowding leading to problems with poor light and ventilation leading to pathogen outbreaks. Each grower manages an average of between 0.5 and 2 ha from which 1–2 tons of green vanilla/ha are obtained in rain-fed plantings, or between 2 and 4 tons of green vanilla/ha in irrigated plantings.
Shade Houses
This is the newest and most intensive system of vanilla production in Mexico. The main feature of this system consists of substituting or complementing natural light with plastic shade nets of 50% luminosity. These nets are placed over the support trees, usually at a height of 3–5 m, as well as along the four sides of the plantings. These “shade houses” are generally small (1000 m² or 25 × 40 m) because of the high costs entailed in their construction. Supports for vanilla vines are either artifi-cial or living trees, but in either case densities are high (1500–2000 individual vanilla cuttings are planted per shade house, equating roughly to 15–25,000 cuttings/ha).
The first yields from this system were reported in 2007. They ranged from 50–514 kg green vanilla/shade house (1000 m²). The main factor producing this variation was most likely fruit drop of immature beans caused by adverse weather conditions (i.e., high temperatures and drought) in combination with management practices. The maximum yield of 514 kg suggests that 5140 kg green vanilla/ha can potentially be obtained, a value similar to shade house systems in other producing countries. However, it is still unclear if this can be accomplished in Mexico, especially considering the large financial investment that is needed.
Main Impacts on Vanilla Production in Mexico
Drought and High Temperatures
An estimated 80% of vanilla plantings in Mexico are affected by drought, principally from March to June, during flowering and the early stages of fruit development. Because droughts manifest at such a critical stage, both the overall production and quality of Mexican vanilla are characteristics, which are especially sensitive to drought conditions.
Disease/Pathogens
Stem and root rot, caused by the fungus Fusarium oxysporum f. sp. vanillae, is the major disease of Mexican vanilla. It results in both the shortening of the reproductive life and mortality of individual plants. The fungus Colletotrichum sp. is responsible for causing premature fruit drop, sometimes at levels as high as 50% of a particular planting.
Pests
The insect Tenthecoris confusus Hsiao & Sailer (Hemiptera: Miridae) (“chinche roja”) is the principal pest on Mexican vanilla (Figure 22.3). It sucks xylem from leaves, stems, and fruits, and can cause the total defoliation of plants. An unidentified species of caterpillar (“trozadores”) also consumes flower buds, but the damage is generally minor.
FIGURE 22.3 Adult of T. confusus Hsiao & Sailer (Hemiptera: Miridae) and the damages it causes in vanilla.
Flowering, Pollination, and Harvest
The first flowering in vanilla occurs in 2–3 years following planting of new cuttings. The flowering season is during March to May. Similar to other countries, pollination in Mexico is achieved manually. Some flowers are still naturally pollinated, and although the natural pollinator has not been documented, it is most likely to be the orchid bee Euglossa viridissima (Lubinsky et al., 2006; Schluter et al., 2007). The method of harvesting in Mexico consists of cutting of entire racemes with the rachis still intact, using shears or knives. The official opening of the harvest in Veracruz is on December 10, and continues through January and February of the following year.
Vanilla Curing in Mexico
Curing begins immediately following the harvest. Most curing is done by individual curers rather than by growers. Curing lasts for 3–5 months, generally from January to May.
Vanilla curing in Mexico is distinct from all other vanilla-producing countries, a fact that has helped secure a demand for Mexican vanilla in the world market. This curing process consists of the following steps:
1. Fruit/raceme separation (“Despezonado”)
This step entails the manual separation of each fruit from the rachis (“pezón”). This step begins with the classification process of the fruits by size and type (e.g., whole, split, small, etc.).
2. Oven killing
This step terminates photosynthesis and cellular activity in green fruits and prevents mature fruits from dehiscing during ripening. Fruits are packaged in small wooden boxes or straw mats (“petates”) and then placed in ovens for a period of 1–2 days at 60°C. Afterward, vanilla fruits are removed from the oven and placed in larger boxes for sweating. The fruits are covered with cotton, sheets, and mats for another 1–2-day period during this first instance of “sweating.” In recent years, some curers in Mexico have switched from using ovens for the “killing” stage to using hot water, as is the process in Madagascar.
3. Sun curing and successive sweats