Gingers for the Louisiana Garden

As our landscapes languish in the Louisiana heat, a wonderful group of plants called gingers thrive and delight us with bold foliage and attractive flowers. Native to tropical or semitropical regions, gingers flourish in the heat, rain and humidity. Despite their tropical origins, many gingers are hardy throughout the state and make excellent, permanent additions to the landscape. Gingers produce a thick, fleshy stem that grows at or just below the soil surface called a rhizome. With a good, thick mulch of leaves or pine straw, the rhizomes are easily protected during the winter. And if the top is killed by hard freezes, the rhizome will re-sprout in the spring.

The plants we call gingers actually include many genera with many different sizes, growth habits and flower shapes. Low-growing gingers, like Kaempferia pulchra, smaller species of Curcuma or Globba, make great groundcovers or clumps at the front of shady borders. Medium-size gingers 3- to 6-feet tall include species of Curcuma, Hedychium and Costus, and the shell ginger (Alpinia zerumbet) grows 10- to 12-feet tall. These larger gingers are excellent choices for accent, screens or at the back of a border.

In their natural habitats, most gingers grow under the canopies of trees in filtered light, although some grow in the open at the edge of water and in sunnier conditions. Most gingers will do best where they receive direct sun for about two to four hours a day, although shell ginger and some species of Curcuma and Hedychium will grow in full sun. When planting gingers into the landscape, choose a location with appropriate light and generously amend the soil with compost, well-rotted manure or peat moss and a light application of an all purpose fertilizer.

Consider planting some gingers in your landscape this summer. Their bold, tropical foliage, attractive flowers and, in some cases, wonderful fragrance will add a lot to your summer gardens.

Bell Pepper Disease

Phytophthora blight of peppers is caused by the water mold Phytophthora capsici, which also attacks tomatoes, eggplants and most cucurbits. This disease is capable of rapidly decimating pepper plants in home and commercial gardens during periods of heavy rainfall, and its management relies on the utilization of a combination of practices aimed at reducing the rate of disease development.

Symptoms may be observed on all parts of the plant. Because the disease is typically initiated by a soil-borne inoculum, disease develops initially as a root and crown rot that is first evident by the wilting of the plants followed by defoliation. Examination of wilted plants usually reveals a characteristic brown lesion at the base. As the disease develops further, inoculum reaches the foliage, stems and fruit. Infected leaves exhibit grayish-brown, water-soaked lesions. Stem lesions are brown to black, and lesions on fruit are grayish-brown and appear soft and water-soaked. Under humid conditions, the white mycelium and sporangia of the pathogen are readily visible on infected tissues.

The utilization of cultural practices that aid in the rapid drainage of excess water and minimize the potential for standing water is crucial. As is true for most diseases, fungicides are most effective for controlling Phytophthora blight when they are applied prior to the onset of disease. Since most fungicides labeled for use against the foliar phase are listed as being effective only for disease suppression, they must be applied early when symptoms are first observed and repeatedly as long as environmental conditions are suitable for disease development. Because this pathogen can develop resistance to fungicides quite readily, it is important to alternate fungicides and follow their label instructions regarding their use. For current information on fungicides available for managing this disease, see the Louisiana Plant Disease Management Guide or visit our Web site www.lsuagcenter.com.

Blossom End Rot on Tomato

Blossom-end rot can occur when sunny days follow a cloudy, wet period. It is a calcium-deficiency disorder in the plant and not a pathenogenic disease. Some cultivars are more prone to this condition.

Calcium moves slowly in plants and even slower in the fruit, so deficiencies can occur even when soil tests indicate that calcium is adequate. Blossom-end rot often occurs on the tomato first. It may also be a problem on peppers, squash and watermelons. It is more common on fruit that is one-third to one-half grown, and it occurs on the blossom end of the fruit.

It begins as a small, water-soaked spot and develops into a dark brown, leathery spot that may involve half the fruit. The surface of the spot shrinks and becomes flat or sunken. Blossom-end rot is caused by a lack of calcium in the developing fruit. The uptake of calcium from the soil by the tomato plant can be reduced by fluctuations in soil moisture – either excessively wet soil or excessively dry soil.

The disease commonly occurs when plants are growing rapidly and luxuriantly early in the season and are then subjected to prolonged dry weather. The disease may be more serious on the windward side of a garden and on staked tomatoes rather than on un-staked or bushy plants.

Prevent blossom-end rot by maintaining a soil pH around 6.5 and uniform soil moisture by irrigating and mulching, and avoid heavy applications of nitrogen.

Calcium nitrate also may be used and applied once per week once you have golf ball sized fruit. Use 1 rounded teaspoon per plant. Apply calcium nitrate into the soil about 8 inches from tomato plant stems.

For more information on these as well as other horticultural topics, call me at 985-446-1316 or email me at bhfletcher@agctr.lsu.edu. You can also check out the LSU AgCenter website at www.lsuagcenter.com.