A Case of Molybdenum Deficiency in New Zealand

Abstract

IN a small private-garden investigation into the disease 'whiptail' of cauliflowers, extreme symptoms appeared in those plants not treated with the group of trace elements manganese, zinc, copper and molybdenum. The matter was therefore studied more closely in the glasshouse. In an experiment involving some twenty combinations of two and three of the elements manganese, zinc, copper, molybdenum and boron with and without lime, and in which phosphate, potash and nitrogen were adequately provided, 'Whiptail' failed to develop. At an early stage of growth, however, all plants not supplied with molybdenum developed an intervenal chlorosis very similar to that described by Arnon and Stout² in molybdenum-deficient tomatoes. The symptoms were much more pronounced where lime had been omitted. This is in line with a body of evidence^5,7,8,11,12 that soil molybdenum is more available for plant uptake in limed or naturally alkaline soil. The unlimed plants in particular also showed the involution of the leaf edges and marginal necrosis seen in the tomatoes. The addition of sodium molybdate to the soil brought about a rapid recovery of the affected plants. No marked growth differences were associated with the symptoms and eventually all plants grew out of the condition. The habit of the plants was not normal in the glasshouse and they were not left to reach maturity.