Chlorotic Foliage Research Articles

Interactions of Ethylene, Temperature, Light, and CO2 on Leaf and Stipule Abscission and Chlorosis in Philodendron scandens subsp. oxycardium1

Abstract Plants of Philodendron scandens subsp. oxycardium (Schott) Bunt. were exposed to ethylene-air mixtures at various temperatures and levels of light and CO2. Plants held in ethylene (2.5 to 10μl/liter air) abscised leaves and stipules, developed chlorotic foliage, and grew poorly. As the levels and duration of exposure to ethylene increased, the rate of leaf abscission increased. Plants exposed to 5μl ethylene/liter air at 23.5°C for 3 days in light abscised more than 50% of their leaves, whereas plants similarly handled but held in darkness lost 20%. At a given level of ethylene, the lower the temperature the fewer the number of leaves abscised. Plants held at 27° at 10 μl/liter air had total leaf abscission. Plants held in ethylene with 5% CO2 or with lanolin-coated leaves abscised fewer leaves than plants without added CO2 or non-coated leaves.

Zinc Deficiency Symptoms of Chrysalidocarpus lutescens1

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.

LIME CHLOROSIS IN SEEDLING ESTABLISHMENT ON CALCAREOUS SOILS

SummaryA comparison has been made amongst a number of species as to the ability of green and chlorotic foliage to fully reverse induced leaf water‐deficits. In all cases it was found that chlorosis conferred a reduction in the ability of the affected leaf to resaturate, compared with green leaves of the same species. Three distinct patterns of behaviour of chlorotic leaves were found in this respect. Permanent damage was caused by leaf water‐deficits as low as 10% in some species, whilst chlorotic leaves of others could withstand 60% water‐deficits before irreversible damage was detected. Green foliage of chlorosis‐resistant species were able to tolerate deficits of from 60 to 85% before resaturation ability was impaired. The ecological implications of these findings are considered, with respect to the establishment and survival of chlorosis‐resistant and susceptible seedlings on calcareous soils subject to periodic droughts.

Linkage of genes affecting tuber color and chlorotic foliage

The gene G which induces iron chlorosis inSolanum vernei when in the homozygous recessive condition is very closely linked to a locus which determines anthocyanin pigment production.

THE FUTURE OF BIRCH FROM THE VIEWPOINT OF DISEASES AND INSECTS

Yellow birch was once the most important species of hardwood in Eastern Canada. During the last 20 to 25 years, "birch dieback" has caused losses in the three Maritime Provinces estimated at 2,400 million cu. ft. A considerable number of species of insects feed normally on birch foliage, but none was found responsible for the disease. The bronze birch borer played a very important role in that its presence may have determined whether a tree succumbed to or recovered from decline. No fungi or bacteria found on twigs, leaves or roots were virulent enough to be considered the cause. No permanent or temporary stoppages were found in water-conducting tissues and occurrence of dieback has not been related to drought. Slight increases in soil temperature caused mortality of rootlets, which resulted in bare twigs, and small, slightly curled and chlorotic foliage. Several symptoms characteristic of virus diseases are being investigated. It is predicted that birch will form a substantial component of future forest stands, but high-grade products will be obtained only through application of intensive silviculture. Some recommended treatments are given.

Response of Field-grown Peaches to Strontium Sprays

The application of a strontium chloride spray to peach trees eliminated a marked chlorosis of the leaves. The trees, Red Elberta variety, were planted in 1946 on a sassafras loamy sand. This soil is marked by a low organic matter content and low exchange capacity. For the past several years the trees have grown rather poorly, and there has been considerable dieback. This past year a fertility program was initiated in an effort to improve vigor of the trees. A dormant spray of zinc sulfate at the rate of 10 lbs/100 gal water was applied in February. The trees had been fertilized in March 1951 with 1000 lbs/acre of a 5-10-10 containing 10 lbs borax, 20 lbs Teemangam, and 10 lbs copper sulfate per ton. Since early growth was still showing dieback, additional borax was applied in April as a spray at the rate of 1/2 lb/100 gal. of green color between the veins. Accordingly, a spray of 0.05% (by weight) of ferrous sulfate + 0.025% sulfuric acid was applied to leaves of a few trees. There was no beneficial response to this spray or to a miianganous sulfate spray of the same concentration. A relatively complete nutrient spray' containing N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, B, S, and Mo was applied, but this too had no effect on the chlorosis. A spectrographic analysis of normal and chlorotic leaves of the same physiological age from the same tree revealed that normal foliage had 10 times as much strontium as chlorotic leaves. There was 0.002% strontium in the ash of normal foliage, but only 0.0002% in chlorotic foliage. Strontium chloride (0.05% by weight) was sprayed on both upper and lower surfaces of leaves and branches of portions of several trees on August 5, 1951. Unsprayed portions of these trees, as well as unsprayed trees, were left as checks. Within 3 days a definite response was noted on all sprayed leaves. They were markedly greener, with little or no areas without normal color. By August 18, all sprayed leaves were normal in appearance (Fig. 1, B); unsprayed leaves still exhibited typical chlorosis (Fig. 1, A).

YELLOW BLOTCH-CURL: A NEW VIRUS DISEASE OF THE RED RASPBERRY IN ONTARIO

This paper reports the results of an investigation into a condition of the Cuthbert red raspberry which is quite distinct from any previously described disease. The disease, termed yellow blotch-curl, is characterized principally by a loose type of curling and pale chlorotic foliage which sometimes shows a yellow blotching and ring spot. The disease has been transmitted by patch-grafting, which indicates that it is of the virus type. It has been transmitted to Cuthbert, Viking, Latham, Herbert, Chief, and Lloyd George varieties, and different reactions have been noted and described.From these experiments it is concluded that "yellow blotch-curl" is distinct from mosaic and leaf curl.