The fruit specialists are working with researchers from the Agricultural Research Service (ARS) field station in Mayaguez, and plant physiologists from Agriculture and Agri-Food Canada (AAFC) to develop a practical tool that can be used to determine the right harvest time of avocados. These activities are part of the research facilitated by the Cooperative Program in Agricultural Research and Technology for the Northern Region- PROCINORTE.

During the visit to farmers avocado fields in Nayarit, the Mexican researchers explained that it is absolutely essential that farmers and packing companies learn not to pick the fruits too early because this affects their quality and market value. If avocados are picked too early, they can leave a very bad taste in the mouths of consumers.

Many growers simply look at the hanging avocados and figure they are about the right size to harvest, but this does not work because size varies considerably depending on weather, soil or plant nutrition, and the number of fruits on the tree. Also, fruit falling on the ground is not indicative of ripening because there are a number of factors that contribute to fruit drop. Trees often naturally abort a certain amount of fruit to provide enough nutrition to the remaining fruits. Fruits picked from the ground or without the stem end still attached should not be sold. Once the stem is off, the fruit might ripen prematurely and be attacked by insects. Also, once they fall, the fruits could become contaminated with microorganisms that can cause serious diseases to humans, and therefore will not meet food safety standards and be unmarketable.

The bottom line is that if the farmers want repeat customers their avocados have to be of the highest quality and consistency. For years, wholesalers have complained that local growers do not know when to harvest so determining the optimal harvest time is crucial for this flourishing industry.

To date, there is no one correct way to determine when to harvest avocados; the method used is to cut and measure their mass content, a process that destroys the fruits. However, according to the Mexican specialists, farmers need to cut many fruits from the trees several times during harvest season to test their ripeness. This procedure causes serious economic losses, especially for the many small farmers in Mexico for which avocados provide an extra source of income.

PROCINORTE has invested in developing a hyper-spectral imaging protocol and a portable analyzer for measuring in situ maturation of avocados. This tool can also be used to assess the maturity of several mango varieties that are important crops for Mexican and US growers. The researcher team works directly in farmers’ fields which allows for full involvement in all aspects of research. Also they work closely with many avocado and mango packing facilities in Mexico, training their inspectors on several post-harvest aspects.

The visit ended in the Research Station of Santiago Ixcuintla where Dr. Osuna, an expert on the use hyper-spectral imaging, demonstrated the use of this tool indicating that he has made thousands of measurements of Hass avocados, to be used by Canadian experts to calibrate the tool. Also the Canadian researchers are developing a portable analyzer to measure fruit maturity during the upcoming season in Michoacán, Mexico’s largest avocado producing state.

Mexico produces about 45% of the world's avocados, especially of the Hass variety. The avocado production is forecast to reach a record 1.24 million metric tons (MT) in the marketing year 2010/11, a 6.4% increase over the previous year. Michoacán is the world leader in avocado production and accounts for 92% of total country’s production. Fresh domestic consumption is 806,119 metric Tons (MT), an 8.45% increase over 2010.

About five percent of Mexico's fresh avocados are exported, and it is forecasted that exports reach 410,000 MT in 2011. Currently an estimated 132,036 hectares are planted with Hass avocados; however this area has increased as producers seek to meet greater international demand for this fruit.

Avocados are also an important crop in California and Florida. The total volume produced in 2010 amounted to more than 149,300 TM. The dominant variety of avocado grown in California is the Hass variety, while Florida growers typically produce larger, less oily West Indian or Mexican varieties including Booth, Lula and Taylor. California avocados are marketed year round and Florida’s market is from June through March.

Canada is a net avocado importer, and consumption of these fruits continues to increase. Multicultural diversity and healthy eating habits might have contributed to a greater appetite for avocados in this country. A box of Mexican avocados sells for about $8 in Canada, while a box of US avocados in the US sells for $30. Canadians pay $0.50 to $0.60 per Mexican avocado in retail stores, while US consumers often pay $1 each for California avocados.

The results of these projects will be used by growers in Mexico and the USA to accurately measure fruit harvest time in the field. The information will also be useful in Canada because it will contribute to make available to importers adequate standards for avocados from the neighbor countries.

For more information please contact: phenriquez@iicawash.org