By Christopher Vincent, Megan Dewdney and Liliana Cano
Bingo is a relatively new and unfamiliar variety, which growers initially sought as a positive alternative. However, it presents some unique production challenges. Bingo is desirable because its high-quality, low-seeded fruits are ripe in October, a valuable harvest window for Florida growers. But in the early years of its propagation, some nurseries began to observe higher Bingo mortality rates than other varieties. They described a stem dieback condition that appeared to be responsible.
Growers were eager to get ahold of Bingo and planted trees that were smaller than the size typical of other varieties. Once the Bingo trees began to reach the field, growers saw dieback. Tree losses were occasionally as high as 20%.
The dieback typically begins at one point along the stem. The death usually begins where there was some minor mechanical injury. Misplaced staples, pruning wounds and abrasions from tree wraps are the most common injuries. The area around the wound appears to die suddenly, and if the lesion is large enough, everything above it can die, too.
Dieback symptoms often look like a sudden wilting, with the leaves still attached on a single branch. Trees are lost when the dieback affects very small plants, with the whole tree not bigger than a single branch of a larger tree. In nurseries, dieback appears to be more common when trees are moved or pruned and is most problematic with overhead irrigation.
University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) research suggests that dieback is likely the overreaction of the tree to the presence of certain fungi that would otherwise not cause any disease. This only occurs when the fungi are present and when woody tissue is both injured and wet. The fungi that seem to induce dieback are common wherever there is moisture.
Fungicide treatments have not been successful in preventing dieback. Based on observations and research, it is suggested that:
1) Nurseries use irrigation methods other than overhead irrigation to produce Bingo.
2) Growers request plants that have not been cut back at planting to avoid unnecessary injury.
3) Growers plant full-size trees, preferably with multiple branches, to help avoid tree loss when stem dieback does occur.
Christopher Vincent is an assistant professor, and Megan Dewdney is an associate professor — both at the UF/IFAS Citrus Research and Education Center in Lake Alfred. Liliana Cano is an assistant professor at the UF/IFAS Indian River Research and Education Center in Fort Pierce.
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