| [Image: Bush Killer Vine] |
| [Image: Bush Killer Vine] |
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Ag News
Invasive Herbaceous Vine in the Landscape
Cold Tolerance of Citrus
Citrus Varieties to Plant in our Area
Fig Varieties to Plant in our Area
Bush Killer Vine
Invasive Herbaceous Vine in the Landscape
I am beginning to get a lot of samples of this weed to be identified at my office. We have had it in the area for some time, but it is showing up throughout the area more frequently.
Dr. Ron Strahan, professor with the LSU AgCenter, indicates this vine, known as “bush killer” (Cayratia japonica), is an invasive herbaceous vine that climbs on and over landscape plants. It lives up to its name of bush killer by blocking sunlight and breaking down shrubs and trees with its weight. A single plant can take over a large area during the spring and summer growing season.
The plant is often confused with Virginia creeper and poison ivy (leaves of three, let it be).
Good control has been obtained with Brush B Gon (triclopyr) using the cut stem treatment – cut the stem to remove the vine foliage leaving a single 3-4 inch tall stem. Mix 6 ounces of Brush B Gon in a gallon of water and spray the freshly cut stems. After 30 days from treatment, it will probably be necessary to repeat, but you should get 90 percent control although you will have to stay ahead of it to keep it under control.
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Cold Tolerance of Citrus
We get this question often about how cold a temperature a citrus tree can stand. I will go over a few variables, but first remember that citrons, lemons and limes are most easily killed by freezing temperatures. Temperatures in the high 20s will readily kill or severely damage these plants. Sweet oranges and grapefruit are somewhat more cold hardy and usually require temperatures in the mid-20s before incurring major damage to large branches.
Tangerines and mandarins are quite cold hardy -- usually withstanding temperatures in the low 20s before incurring significant wood damage. The above information refers to leaf or wood and tree damage. The fruit itself easily freezes at 26-28 degrees that last for several hours.
The actual temperature at which tissue of a given plant will freeze and the degree of damage sustained are functions of a number of factors in addition to the species and variety involved. Some of the more important are the following:
- The freezing temperature reached.
- The duration of the freezing temperature.
- How well the plant was hardened or conditioned to cold before freezing temperatures occurred. (Were there prior cold snaps before the freezes?). Hardened citrus plants may be able to withstand 5-6 degrees lower than unhardened plants.
- Age of tree. Mature trees often withstand colder temperatures than young trees.
- Healthy trees are more hardy than stressed trees.
- Trees growing on bare ground have a higher survival probability than trees growing in turf areas. The heat from the ground can radiate up on bare areas as opposed to being trapped by turf areas. This can be 3-5 degrees difference in the canopy of the tree.
We generally recommend you protect your citrus when the temperatures will be below 27 degrees for an extended period of time. This protection is for home citrus practices generally and should include:
- Cover the entire plant, trying to make sure the foliage is not touching the covering.
- Extend the cover all the way to the ground and secure with bricks or other heavy objects so wind does not blow it up.
- Cover must be removed when temperatures rise above freezing.
Hopefully we won’t receive killing temperature to our citrus, but the above can give you suggestions to help protect the trees if needed.
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Citrus Varieties to Plant in our Area
Our Citrus Production Guide has a list of recommended varieties. It is LSU AgCenter publication 1234. I won’t list them all, but a few are of really good quality.
- Satsumas – Owari, Brown Select, Louisiana Early and Early St. Ann.
- Sweet Oranges – Louisiana Sweet, Washington Navel and Moro Blood Orange.
- Grapefruit – Ruby Red and Rio Red.
- Kumquats – Nagami and Meiwa.
- Lemons – Meyer
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Fig Varieties to Plant in our Area
- Celeste – small fruit – 10-15 grams each.
- Brown Turkey – small to medium – 20 – 30 grams each.
- LSU Purple – small to medium – 20 – 30 grams each.
- LSU Gold – large fig – 35 – 50 grams each.
- Alma – small to medium – 20 -30 grams each.
- Kadota – medium – 25 -30 grams each.
Fig for Commercial and Home Production in Louisiana, LSU AgCenter Publication N. 1529, has all of these varieties in them plus information on how to grow and care for figs.
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