The Cashew and You

Friday, March 30, 2012

BY RICHARD J. CAMPBELL

FAIRCHILD TROPICAL BOTANIC GARDEN

As published in the Miami Herald

Most everyone is familiar with the cashew; among the most delicious and expensive of the nuts available in our supermarkets. However, most are unaware of the other parts of the cashew plant that we can grow and enjoy. Further, the world of the cashew has changed in the last decades and it is now feasible to grow, fruit and enjoy the cashew in South Florida.



The cashew is in the mango family and is native to Brazil. It is a commercial nut crop in its home country and in many of the dry tropical zones around the world. New selections have been made in Brazil andIndia that are dwarf, productive and add a new dynamic to the venerable cashew. Today one will not find only cashew nuts, but increasingly the cashew “apple” is becoming a more popular product around the globe.

The cashew apple sits just above the nut at the ends of the branches. The cashew apple can be red, yellow or green and many shades in between. They have a striking beauty on and off the tree given their waxy skin and uniform bell shape. Cashew apples were historically astringent until fully ripe. Anyone who has bitten into an unripe cashew apple of old will not soon forget, but in the last decades new non-astringent selections have been made that have expanded the potential for the cashew apple as a fresh fruit. Today you can find modern non-astringent cashew apples in the supermarkets of BrazilCentral America and Africa.

And, what does all this mean to the South Florida homeowner? Simply, now we have access to good quality selections of cashew that can be successfully grown and fruited in the home garden. The tree is a beautiful ornamental in itself, with shiny dark green leaves and a pleasing structure. The good selections of cashew sold today in reputable nurseries of South Florida are mostly dwarf selections that will begin to flower and fruit at less than 2 years of age. You should ask the nurseryman to be sure. The dwarf cashew is a sight to behold, highly productive and selected for good cashew apple quality. They are so small in fact that they can be successfully grown in containers. 

The cashew tree does not require it, but will thrive in acid soils. Unfortunately, south of Broward County we few areas of acid soils, so mulching to amend our poor native soils is a good idea for optimal tree growth. Trees should be placed in the full sun, although a high canopy of trees will provide an added degree of protection from cold damage. A cashew tree with light shading will still perform well, growing and fruiting at a reduced rate, but having a better overall appearance and better survival during freezes.

The cashew is a fast grower in the warm months and will begin to flower usually before the second year of planting. Cold temperatures and low humidity winds in the winter and spring will damage the tree. The cashew can withstand temperatures down to freezing, but if there is frost the tree will sustain considerable damage. Following a severe cold spell the cashew will lose much of its foliage unless well protected. Young trees will be lost to cold winter temperatures and should be protected in the first years of planting.

Fertilization should be made two to three times per year during the active growing season. The bests months are May, June and September. Do not fertilize later than September, as this can increase the vigor of the tree in the winter and make the tree more susceptible to cold damage. Remember that even when protected the cashew tree will have leaf browning and drop during the winter months. Fall and winter fertilization will only worsen the trees response. 

The tree is in the mango family and suffers from the same anthracnose disease that causes the black spots on mango fruit. In cashew the anthracnose damages the blooms and can cause crop loss in the warm and humid months. In general it is best to keep your cashew tree as dry as possible. They should not be irrigated in the home landscape. If they are irrigated the tree may grow well, but the fruiting will suffer.

The dwarf varieties will require almost no pruning, save a little bit of shaping following the crop. The fruiting is typically in the early summer and can spread over several months. The cashew apple can be harvested when they are fully colored on the tree. If they are non-astringent they can be eaten while still firm, but it they are a standard selection they must be left to fully ripen before eating. 

The cashew apple is eaten fresh and is also one of the most refreshing juices among any fruit. The flavor is reminiscent of mango, with an intense sweetness and slight tart bite. All colors of cashew apples can be eaten and there is little flavor difference among the colors. The nut of your cashew tree is more problematic. The cashew, being a member of the mango family, has irritating latex that can cause severe rashes and allergic reactions. The latex occurs throughout the plant, but the highest concentration is in the shell of the raw nut. You must use caution in handling the raw shells and the raw nuts themselves also contain some irritating latex, but to a lesser extent. Before the nuts are eaten they should be roasted. Most people will not go the lengths needed to produce their own cashew nuts, sticking instead with the beautiful and tasty cashew apple.  

The cashew apple is a legitimate tree for planting in the home garden. If we have heavy frosts during the winter you may lose your tree, but in warm times the cashew will grow well and with the new selections, provide you with tasty non-astringent cashew apples. And who knows, with climate change we may all be growing cashews for our homes.