The hot and rainy weather has brought out the annual anthracnose disease for mirlitons. See the last summer's blog entry here on this disease (I have added a photograph and link to more photos) which discusses how to recognize the different signs of powdery mildew and anthracnose. The growers guide on the web site has additional information. Anthracnose infects almost all mirliton plants, especially in their first year, but depending on proper care and hopefully a low rate of evening rain showers, the disease will only affect a few stems and when those die, new stems will return.
Mirliton leaf infected with anthracnose plant disease. Note different browning pattern and the distinctive "shot hole" in the middle of the brown tissue, which does not occur with powdery mildew (anthracnose, unlike powdery mildew, can live on dead plant tissue and literally "eat a hole" through the plant)
I just posted to our FAQ page a comprehensive article on powdery mildew in Mirlitons. I tried to get it to fit on the blog but apparently blogs are for concise thinkers--that rules me out. View the article at http://bitly.com/IFpLda and visit the FAQ page and Garden Blog for new useful information.
Lance Hill, Mirlitons.Org
Ishreal Thibodeaux Variety Mirliton. This is the only pure-white mirliton that we know of in the South.
Because of the warm winter, we have been getting an early crop of mirlitons that started in February. I noticed these gelatinous clear growths on the immature fruit and then spotted an immature and mature leaf footed bug (stink bug) that feed on the fruit.
Fruit fluids (cytoplasm) leaking from fruit and jelling. Note flower and fruit are dead
Dr. Dale Pollet of LSU identified these growths as the cytoplasm (fruit fluids) oozing from the fruit after the leaf footed bugs have penetrated the fruit skin to feed on it. In this case, attacking the very small immature fruit kills the fruit. I have seen the insect also try to feed on mature fruit which does not display any immediate damage but will manifest as brown bruising after the fruit is picked. They also spread plant diseases. The best method of control is to pick the insects off by hand, but they can be treated with organic fungicides. If you use an organic pesticide, be careful that it is not toxic to bees (it is pollination season) and that it is not phytotoxic (can damage leaves in high temperatures). Test it on a few leaves for one week first.
Immature Leaf footed Bug on Mirliton Leaf
Leaf footed bug feeding on flowers. They can block pollination tubes.
Mature Leaf Footed Bug (stink bug)
I talked to someone the other day who had purchased a mirliton plant from a local nursery and it was not growing well. When I asked him to find out where the nursery obtained the seed, it turned out they had bought them from Wal-Mart. Most of the mirlitons (chayote, Sechium edule) sold in groceries are imported from Costa Rica where they are grown at altitudes of over 3,500 feet. My recent research into the USDA records indicate that as far back as 1920, the USDA's experimental station in Brooksville, Florida had discovered that this high-altitude variety will not grow in our hotter, heavy-rain Gulf Coast climate. Those findings were published in 1947 in a Botany Journal.
Field research by Dr. Moha Dutta Sharma at the IAAS in Nepal in the 1990s found genetic variety in mirlitons--some were more suceptible to disease and fungus than others--and some flowered only male flowers when transplanted into different climates. DNA research in the last ten years has scientifically established that there are clear genetic differences among domestically cultivated mirlitons in Latin America.
I am not arguing that a determined gardener can't get these store-bought varieties to grow, but these mirlitons are intended for consumption, not garden seed. Moreover, if a grower manages to get an imported variety to grow, it can potentially cross-pollinate with our few remaining heirloom mirlitons and reduce our home-grown line's disease resistance or yield.
There are only two ways to determine if you are purchasing an heirloom mirliton--one that has been successfully grown for decades in Louisiana without the use of pesticides and fungicides. First, you can obtain seed from us at mirlitons.org. We research varieties, interview growers, and do site visits on farms to determine if plants are grown naturally. Unfortunately because of the crop disaster we had last year (late flowering and early cold temperatures destroyed most of the heirloom crop), we do not have any seed to distribute.
While our seed distribution is free, we do expect next fall that our growing network of heirloom growers will produce thousands of seeds and they will be available for sale at nurseries that we certify as only selling home-grown Louisiana mirlitons.
The second way to determine if a mirliton plant/sprout is an authentic Louisiana heirloom is to find a grower who has grown the same variety for years. Commercial imported varieties sold in stores did not enter our markets until about 20 years ago. There are still growers in South Louisiana who are growing varieties that are more than 20 years in production, so they clearly were introduced before the Costa Rican chayotes became available.
So consumer beware! Anyone can get a store-bought imported mirliton to sprout in a container and grow a few feet. Unfortunately, the consumer will be on the short-end of the stick and ultimately our traditional home-grown varieties will be placed at risk.