Collapse of ‘Murcot’ Citrus Trees1

Abstract

Abstract The ‘Murcott Honey Orange’ is grown rather extensively in Florida and is highly desired because of its fine flavor and dark orange colored flesh. Its origin is unknown, but the ‘Murcott’ is probably a hybrid of mandarin and sweet orange parentage. This variety bears very heavy crops with much of the fruit set in clusters. These extremely heavy crops result in a collapse of the trees near the time of fruit maturity. Depending on the severity of this decline, the trees may require from one to several years to recover (Figs. 1,2,3) or in extreme cases, die. The leaves and fruit from severely affected trees turn yellow and drop followed by dieback of the branches. These symptoms appear in December and January and become progressively worse as the fruit matures. Fruit on less severely affected trees are usually small and fail to develop the dark orange color characteristic of the variety. The problem of ‘Murcott’ collapse is probably the main reason this variety is not more widely grown. Knorr and Collins (1) previously described this condition and reported that in some cases, severe root deterioration occurs. The problem apparently is not limited to ‘Murcotts’ since similar symptoms have been reported in California for the ‘Wilking’ and ‘Kinnow’ mandarins (3).