tropical agriculture

TROPICAL AGRICULTURE (IN THE SUBTROPICS!) (results of Musa cultivation)

Update - Go to Tropical Agriculture Part II for recent material!

Introduction            Growing delicate tropicals in a sub-tropical climate is a challenge during the winter season. The
goal is to produce fruit and have it ripen during the warm season. With this in mind I embarked on an
experimental non quantified project to grow semi delicate cultivars of desert Musa bananas at my
home in Brownsville, Texas. What follows is a description of the environment and the cold hardiness
as observed during the current winter season. The cultivars being evaluated include the following:
Rajapuri, Dwarf Cavendish, Super Dwarf Cavendish, Grand Nain, and Dwarf French Horn Plantain.
Also compared will be the Orinoco (Horse plantain, Bluggoe) which grow everywhere in the Lower
Rio Grande Valley of South Texas. The Orinoco cultivar is well adapted here needing no special
soils, or protection.
Location/Climate          Brownsville, Texas is located at the extreme southern tip of Texas - approximately 26^o N., 97.5^o W. Located just 180 miles north of the Tropic of Cancer, the climate is classified as BSh in the Koeppen climate system. This translates into sub-tropical/tropical semi-dry.
        In simple English this means a very long hot summer, and a short, mild winter. In fact, the Dec.-
Feb. average temperature of 61.1^o F. is warmer than San Diego, California (57.8^o F.), Tampa, Florida (60.7^oF.), and Orlando, Florida (60.5^o F.) (Climate Prediction Center).   Extreme South Texas, thus, has the warmest winter weather in the continental United States west of South Florida. What the data do not show are the occasional blasts of cA (continental Arctic) air masses. The strong and very dry northwest winds wreak havoc with leafy tropical vegetation such as bananas. Although classified as USDA climate zone 9B (winter lows between 25^o-30^o F.), it is very rare to have temperatures below 30^oF. When these do occur, about once every five years, it is the result of a massive Arctic invasion which drives freezing temperatures as far south as Miami in Florida. These freezes are devastating in the Lower Rio Grande Valley.
        The summers are long, hot, and humid, the June through August average at Brownsville being
83.9^o F., warmer than that of Miami at 82.4^o F. (Climate Prediction Center). It is a very long effective
growing season indeed.
        A curious note about the climate is the combination of high humidities and low rainfall. Dew points for most of the year are between 60-70^o F. making an excellent environment for Musa leaves. However, the average precipitation of 25-26 inches is erratic and very unevenly distributed throughout the year. Supplemental irrigation is necessary.
Soils/Cultivation          Brownsville is located on the lower course of the delta of the Rio Grande. As such the soils are
deep and alluvial. Texture ranges from heavy clay to silty clay loam. My specific soils are the latter.
Drainage is moderately good. However, for optimum banana growth the soils need to be worked and
amended. In particular I have added to all my bananas well rotted cow manure and continually
add "homemade" compost.
        All my plants are grown outside - there is no greenhouse. On two cold nights (temperatures
32-35^o F) in December, 1997, I did bring the potted specimens inside and covered with sheets some of the Super Dwarf Cavendish that have already been planted.
        While in containers I do use chemical fertilizers - mainly Peters 20-20-20. There is no muriate
of potash or ammonium sulfate in the Peters solution. Those two compounds can raise the salts and
pH of the soil. The ammonium can raise the pH and the chlorine in the KCL can break loose from the K
and join with sodium in the soil to cause a definite salinization problem (Peavy 1979:45).
        Once in the ground I use exclusively organic techniques preferring to let the earthworms do the work. Compost and manure are continually added around the base of the plants. If I do go to inorganically produced chemicals I will use a foliar spray of the Peters 20-20-20 solution to
minimize the previously mentioned soil problems.

Cold Hardiness Winter 1997/98          Planting of Dwarf Cavendish and Super Dwarf Cavendish began in July of 1997. Anticipating one
year for "shoot," I chose July. This would avoid winter "choke throat," a common problem with
Dwarf Cavendish cultivars (Robinson 1996:59-60).
        While most of the country has been experiencing mild "El Nino" conditions, December in South Texas saw the several intrusions of cold, windy mountain air, the source area being the Great Basin. There was a combination of cold windy weather with temperatures in the mid-thirties for a short period of time. The Weather Service even reported snowflakes, almost unheard of in South Texas. While there was no freeze, the temperature on two nights flirted with 32-33^o F.
        Interestingly, 250 miles further south in Mexico, the area between Cd. Mante and Cd. Victoria did experience a killing freeze in the lowlands when a cold air mass spilled out of the plateau into the valleys. I saw numerous mango orchards which had been defoliated by the cold; in many areas the banana leaves were brown. No such thing happened in Brownsville as my mango trees continued to flower and are now producing fruit. The closeness to the Gulf of Mexico must have spared us.
        January and February here were quite warm averaging 65.3^o F. and 64.5^o F., the former being
a whopping 5.9^oF above average. There has been very little rainfall since December; as of April 4,
there hasn't been two inches of precipitation in four months! The winter weather of 1997-98
could be summarized as warm, very dry, and very windy.
        With all the above in mind, I'll quit my long-winded summary of background and describe how my
bananas fared during the preceding winter.

Cold Hardiness and Banana Cultivars MOST HARDY

Cultivar	Temperature	Comments
Orinoco	Most hardy, 30-32^oF. with wind	Almost grows wild here, appear to be unaffected by cold. I don't grow them!
Rajapuri	Mature leaves hardy 32-35^o F. with wind. Emerging leaves damaged by wind and temp. in the thirties.	I like them! They have done well over the winter months.

MODERATELY HARDY

Cultivar	Temperature	Comments
Ensete maurelii	35-38^o F. with wind, near freezing with calm conditions	Has done quite well during the winter months. Very small bare rooted specimens now have leaves over 5 ft. tall.
Dwarf Cavendish	35^o F. with calm conditions, leaves will yellow if colder, 38-40^oF. with wind.	Not as cold hardy as the literature suggests. It is the hardiest of the AAA bananas. I should get good fruit if there is no more cold weather.
Super Dwarf	38^o F. with calm conditions, about 40-42^o F. with wind.	This is definitely not as hardy as Dwarf Cavendish. While the leaves aren't destroyed with temperatures in the thirties, they are damaged.

COLD SENSITIVE - all of the following suffer leaf damage with wind and temperatures in the
                               low forties. They need protection from the wind.

Cultivar Temperature Comments

Dwarf French Horn Plantain Leaf damage mid forties with wind, on a calm night they handle upper thirties It is not supposed to grow here - I think I can get it to fruit my next September.

Grand Nain
Slightly more cold sensitive than the Dwarf Plantain. It does not like wind. I've been able to fruit these in the past. The problem is wind protection. I don't know how the Israeli's grow thes commercially!

Dwarf Jamaican
(Cuban) Red Needs to be protected when the temps. are in the lower forties, wind or calm. Tropical and slow growing. I'll keep this in a container for a year.

Photograph Album Winter Growth April 5, 1998 What you see in the following photographs is mainly winter growth of various Musa cultivars
in South Texas. No plant is more than eight months old. They were not greenhoused during the
winter, although some were moved inside during cold nights. I will have progress photographs
in mid July. Cavendish Cultivars (AAA)

Dwarf Cavendish - 4/5/98 Dwarf Cavendish - 4/29/98 Source - cutting from established grove. I cut a sword sucker on July 1, 1997. It took about a
month to regenerate and produce new leaves. The specimen in the photograph shows eight months
of growth. The fence in the background is six feet high to give a scale perspective. This plant has
been in the ground all winter; many of the lower leaves turned yellow and were cut off. Going Bananas
lists one year for a Dwarf Cavendish to fruit in the subtropics - I expect that to be July or so.

Update - May 5, 1998 The shoot came much earlier than expected; inflorescence started
about April 10. This is months earlier than I had expected. While it is common here to have
a shoot in August or September, after a long warm season, this is the first time I have ever had
a Dwarf Cavendish produce a viable shoot this early in the season.

Super Dwarf Cavendish Source - purchased as a three gallon specimen from Kay's Cactus Garden in Olmito, Texas, August 1,
1997. This plant has been in the ground since August 1, 1997. Compare its size to the Dwarf
Cavendish above. In all fairness to the Super Dwarf Cavendish, it is in a site that was unprotected
from the northwest wind. Notice the wind burn on some of the lower leaves. I have no idea as
when to expect inflorescence.

Grand Nain Source - Stokes Tropicals. This plant was received bare root, minus leaves, but with 2 ft. of
pseudostem on October 3, 1997. What you see is six months of growth. It is very wind sensitive.
During the winter it was kept in a container; I was continually moving it depending on weather
conditions.

Ensete Maurelii

Ensete Maurelii Source - Stokes Tropicals. This plant arrived as a small bareroot corm on Sept. 25, 1997. You are
looking at a little more than six months growth. The leaves seem to be temperature hardy, but are
shredded because of the windy conditions of the past few weeks.

Other AAB Cultivars

Rajapuri Source - Grimsell's Seed Company, Harlingen, Texas. This plant was purchased November 11,
1997. It was rootbound and chloritic in a one gallon container. Needless to say, its health has
improved dramatically. Compare the conditions of the leaves with those of the Dwarf Cavendish
above. True, it is in somewhat of a more wind protected location, but all of these winter leaves
appear to be healthy.

Rajapuri, Tissue Cultured Source - Stokes Tropicals. I received this November 24, 1997 as a small tissue cultured plantlet.
Growth was immediate and vigorous. I highly recommend purchasing tissue cultured planlets. There
is little damage during shipping and no time consuming recovery period.

Dwarf French Horn Plantain Source - Jene's Tropicals, St. Petersburg, Florida. This plant was shipped across the Gulf of Mexico, arriving October 31, 1997. It was shipped, at my request, complete with roots, soil,
and three gallon container. The trip, apparently, was rough on the plant, I had to cut all the leaves.
It has regenerated quite well - the Dwarf French Plantain is the one next to the Mediterranean
fan palm. The Dwarf Plantain is supposed to be less hardy than the Grand Nain. However, I have
found just the opposite - it suffers less from the cold and wind than the Grand Nain. The above
specimen is half grown; I expect inflorescence by August or September.

Proof of a Mild Winter Fruit Laden Tommy Atkins Mango

Tommy Atkins Mango with Fruit Here is proof of a mild winter. The above Tommy Atkins Mango is loaded with developing
fruit, April 4, 1998. I have had this tree flower and fruit before, but never at this early
date. The tree flowered November-December, and the fruit has been developing all winter.
This is two-three months ahead of schedule.

        I'll be the first to admit that all the preceding would not by anything out of the ordinary for
a corresponding latitude in Florida - Miami or Fort Meyers. And I also am aware that next winter
may be a lot harsher than the past one. Those of us in South-Central and Southeastern U.S. may
not have it so easy next year.
        Just arrived from Going Bananas are some corms of Zan Moreno Cavendish and Double (Mahoi)
Cavendish. If I can find a few more square inches in my overcrowded yard I'll give them a try. There will be new photographs in mid July.
        I'd like your comments, particularly relating to fertilizing. I'd like to know some other
methods for adding potossium to the soil.

Gene J. Paull
Physical Science Dept.
University of Texas at Brownsville
Brownsville, Tx., 78520
(956) 574-6681
E-Mail: paullgj@utb.edu
Homepage: http://blue.utb.edu/paullgj

Literature Cited Peavy, William S.
1979 Southern Gardener's Soil Handbook. Houston, Texas: Pacesetter Press.

Robinson, J.C.
1996 Bananas and Plantains. United Kingdom: CAB International.

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