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- Author or Editor: Stephen H. Futch x
- HortTechnology x
Florida citrus groves of sweet orange (Citrus sinensis), tangerines (Citrus reticulata), and grapefruit (Citrus paradisi) experience an annual tree loss of 3% to 4% due to various causes of tree decline. Commonly used tree removal methods in Florida include “pushing,” which lifts most of the root system completely out of the soil, or “clipping,” which shears the tree off above the soil line leaving the tree stump and root system in place. Several operational and economic advantages and disadvantages exist for both tree removal systems. There are also potential problems with citrus resets that can occur due to foot rot (Phytophthora nicotianae) and citrus nematodes (Tylenchulus semipenetrans) that remain in the soil after tree removal. To investigate reset tree performance after “pushing” versus “clipping,” a study was conducted in three groves representative of three production regions in Florida to compare the impact of tree removal method on the pest/pathogen status and growth of resets over a period of 4 years. Based on the findings, tree removal by “pushing” or “clipping” appears to have minimal effect on subsequent pest and pathogen status and performance of citrus resets. Therefore, the method of tree removal should depend primarily on operational and economic considerations.
Citrus greening or Huanglongbing (HLB) has caused sweet orange (Citrus sinensis) yield in Florida to decrease by 55% since the disease was first discovered in 2005. As a consequence, the profitability and sustainability of citrus (Citrus sp.) production in Florida have been jeopardized, as evidenced by the 62% reduction in the number of citrus growers statewide. Because there is still no effective treatment or management strategy to cure the disease, it is crucial to optimize grove practices and management. The use of improved rootstocks could increase the tolerance of citrus scions to biotic and abiotic stresses, thereby allowing growers to cope better with the impact of HLB in the field. We used yield data collected from commercial trials over the course of multiple seasons to assess the side-by-side performance of various commercially available rootstocks developed by the two major breeding programs in Florida in HLB-endemic field conditions. We found that some of the rootstocks attained not only statistically significant differences in yield relative to the control but also meaningful differences in revenue. Those estimates provide evidence regarding the effect of rootstock during the first few seasons after planting. Our findings are useful to improve growers’ decision-making processes regarding rootstock selection for new groves.
The main objective of this study was to evaluate the suitability of the DEIAFA drift test bench system (Dipartimento di Economia e Ingegneria Agraria, Forestale e Ambientale; University of Torino, Italy) for assessing drift potential of a citrus (Citrus sp.) herbicide applicator. The study involved testing the effects of spray drift shield, nozzle type, and ground speed on drift potential of the applications. It was carried out in randomized block design within a split-split-plot experiment with five replications. A computational analysis procedure for evaluation of deposit values, measured along the test bench, was developed to compare the treatments in terms of a drift potential index (DPI). The methodology provided repeatable results. Among the treatments, ground speed was the main factor affecting the DPI. Both nozzle types tested [flat fan extended range nozzle (XR) and wide-angle deflector nozzle (TT)] showed higher DPI at faster speed. Decreasing the ground speed from 6.0 to 3.0 km·h−1 decreased the drift potential on average ≈35%. The performance of XR nozzle was improved by the presence of spray drift shield (27% reduction in DPI). However, the shield did not affect the drift potential of the TT nozzle significantly. The results were significantly affected by the wind velocity normalized by its direction relative to the sprayer travel; therefore, the tests should be carried out in relatively calm wind conditions, as much as possible.