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Abstract
Boron deficiency symptoms of hydroponically-grown Ficus elastica Roxb. ‘Decora’ included plant stunting, deformation of immature leaves and necrosis of terminal bud. Excessive boron caused the undersides of mature leaves to have brown, circular lesions with chlorotic halos, starting at leaf margins. Affected leaves abscised prematurely. Boron deficiency symptoms of hydroponically-grown Chrysalidocarpus lutescens Wendl. included stunted growth, chlorotic mottling and streaking of leaflets and eventual death of immature leaves and terminal bud. Inflorescences bore necrotic fruits and died prematurely. Toxicity symptoms included leaflet mottle chlorosis and premature death and tip-bum of all leaves.
Abstract
White lesions, symptoms of chilling injury, appeared in Sansevieria trifasciata (de Wildm.) N. E. Br. cv. Laurentii for one month following exposure to temperatures ranging from 2° to 8°C Cold-injury symptoms increase with increasing levels of N and K.
Abstract
The responses of 13 cultivars of Hibiscus rosa-sinensis L. to Meloidogyne javanica (Treub) Chitwood and of 12 cultivars of H. rosa-sinensis to M. incognita (Kofoid & White) Chitwood were determined in 2 greenhouse inoculation experiments. ‘Pride of Hankins’ was highly susceptible to M. javanica, ‘Philipino’ was highly susceptible to M. incognita, and several other cultivars showed moderate levels of galling from the latter species. The cultivars which were least susceptible to both nematode species were ‘President’, ‘Florida Sunset’, ‘Old Gold’, ‘Go-Go Girls’, ‘Anderson Crepe’, and ‘Delight’.
Abstract
Symptoms of zinc deficiency in hydroponically-grown Chrysalidocarpus lutescens H. Wendl. included plant stunting, uniformly chlorotic foliage and very small leaves bearing stubby, clustered pinnae.
Abstract
Philodendron oxycardium was grown in a medium of peat mosssand 3:1 with applied nutrient solutions varying from 5 to 450 ppm of N, 0 to 50 ppm of P and 0 to 444 ppm of K. In the soil, these concentrations were somewhat increased by evaporation. Most of the leaf analyses were in the ranges 1.5 to 3.5% N, 0.08 to 0.40% P and 1.5 to 5.5% K. Within these ranges, growth decreased with an increase in N content and increased with an increase in P and K.
When inoculated with Xanthomonas sp., disease decreased with increasing N and was not much affected by K. Phosphorus had little effect on disease except in one of the 6 experiments, where a reduction was found when the leaf P exceeded 0.40%.
Old green leaves were more susceptible to inoculation than young. The disease did not reappear in plants after all leaves were removed and stems had produced new foliage. The pathogen did not carry over in stems, roots or potting medium.