Air potato

Air potato fruit and leaf

Photo courtesy Karen Brown, University of Florida

We are no stranger to invasive, climbing, vining plants in the New Orleans area. They seem to have the ability to swallow trees, houses, fence lines and, if you stand still long enough, gardeners.

While many home gardeners may be familiar with cat-claw (Dolichandra unguis-cati) and bush-killer vine (Cayratia japonica), there’s a new vine in town and it grows like crazy here.

Air Potato (Dioscorea bulbifera) is a perennial vine native to Africa and the Asian continent that is now found in 13 Louisiana parishes. It is a member of the yam family but is not edible and has a bitter flavor. This vine has broad, alternate heart-shaped leaves and recognizable storage organs that resemble small potatoes attached to the leaf axils. It also produces underground tubers resembling small, oblong potatoes.

Air potato is an invasive species. It can grow up to 8 inches a day in a dense mat and can quickly shade and crowd out other vegetation, spreading quickly as the aerial bulbils (air potatoes) are moved by humans and animals.

Controlling air potato involves a few different tactics. Removing the vines, taking care to destroy or discard the entire plant, is a good first step. Take extra care to pick up and remove all of the aerial bulbils, as each one has the potential to become a new vine.

Herbicides that contain glyphosate can be used, but be careful to spray only the target plant. If the air potato re-sprouts, spraying with an herbicide helps to kill the roots and tubers that you may have missed. It may take several herbicide applications to kill the tubers.

A parasitic insect known as the air potato leaf beetle (Lilioceris cheni), introduced in Florida, feeds on the plant's foliage and can be an effective biocontrol for air potato vine.  This beetle has not been established in Louisiana yet, so it's best for gardeners in Louisiana to control this vine by removing it and treating often with herbicide until it is eradicated.

For more information on this issue and other gardening topics, please visit the LSU Agricultural Center website at www.lsuagcenter.com.

My navel oranges are splitting and falling from the tree. How can I fix this problem? — Don

Oranges and other citrus fruits can split for a couple of reasons. When the fruit is forming, it is drawing moisture and plant sugars into the fruit. The rind is also growing as the fruit swells and fills. If you are not regularly irrigating your fruit trees, a heavy rainfall can cause the trees to take up more moisture than the rind can hold, causing it to split.

This can happen especially after a dry period followed by excess rainfall. Over-fertilization can also cause this to happen, as can tree stress, but typically when citrus splits in southeastern Louisiana, it is due to excess rain. Water or irrigate your citrus trees regularly during dry spells to reduce the chance of fruit splitting. — Anna Timmerman