Advice on heat tolerant Blueberry varieties for tropical area

Asked June 1, 2018, 9:24 AM EDT

I am PhD student in Food Science at MSU and a volunteer for Asian Agriculture community, I got a question about heat tolerant Blueberry varieties, could you please help me with this question We are living in the highland region of Vietnam in Dalat city. The local climate can be briefly described as followings: - Subtropical highland climate under the Köppen climate classification (Cwb) - The city is located at attitude of 1520 m above the sea with year-round temperate weather. - The average temperature is 14 °C (57 °F) - 23 °C (73 °F). The highest temperature ever was 31.5 °C (88.7 °F), and the lowest was −0.6 °C (30.9 °F). Mist covers the adjoining valleys almost year-round. - There are two separate seasons. The rainy season lasts from May to October, and the dry season is from November to April. The average annual precipitation is 1,770mm. - During rainy season, temperature at night ranges between 10-15°C (50-59F) I’ve heard that there are several heat tolerant Blueberry varieties such as the ones listed below. Could we plant the below varieties in Dalat? or are there any other varieties which you can recommend for us? 1/ Southern Highbush blueberries : - Which requires require 150 to 600 chilling hours to induce fruit production, unlike its Northern relatives that can require upward of 1,000 hours. - The early season cultivars "O'Neal," "Sharpblue," "Misty" and "Star" are good producers in warm climates. "Legacy," "Jubilee" and "Southmoon" are mid-season choices. "Ozarkblue" is a late season cultivar that produces fruit just slightly ahead of rabbiteye blueberries. 2/ Rabbiteye - Rabbiteye blueberries (V. ashei) are a species native to the Southeastern United States, where they evolved in a climate with hot summers and winters that are often mild. Rabbiteyes need 350 to 700 chilling hours. - Common cultivars that requires less than 400 hour chilling, including "Prince" (350 hours), "Woodard" (350 hours) and "Brightwell" (400 hours). Others require no more than 550 hours -- among those are "Climax" (450 hours), "Alapaha" (500 hours), "Austin" (500 hours), "Premier" (550 hours) and "Vernon" (550 hours). Thank you very much for your great support

Ingham County Michigan blueberries blueberry production blueberry varieties

1 Response

Your concern should not be heat tolerance but low chilling requirement. Do you have any idea of the number of chilling hours (between 1 and 6 C) this region gets? Here in Michigan we grow Northern Highbush which requires 750 to 1000 chill hours.
Rabbiteye blueberries are falling out of favor as there are many Southern Highbush varieties being developed. I am not familiar enough to recommend specific Southern Highbush varieties but most of those you name are older varieties and you will want to look at newer varieties. They have even begun to develop No chill varieties which allow evergreen production in the semi tropcs and under high tunnels.
Look at varieties developed by the University of Florida. Here is a link to a Florida publication on blueberry culture. http://edis.ifas.ufl.edu/mg359
There are extensive breeding efforts looking at low chill and even no chill blueberries. You might want to look at Fall Creek Nursery which exports blueberries world wide and has a wide range of plants available both low chill and no chill http://www.fallcreeknursery.com/