Yellows


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yellows

[′yel·ōz]
(plant pathology)
Any of various fungus diseases of plants characterized by yellowing of the leaves which later turn brown, become brittle, and die; affects cabbage, lettuce, cauliflower, peach, sugarbeet, and other plants.

Yellows

 

diseases of plants— such as aster, celery, and peach yellows; witches’-broom of delphinium; purple top wilt of potato; and big bud— caused chiefly by mycoplasma-like organisms and by viruses.

Diseased plants are stunted and chlorotic, with many lateral shoots pressed to the main stem. The flowers have elongated sepals, deformed corollas that turn green, and an ovary that germinates into leaflets. Yellows attack many plants (potato, clover, onion, carrot, ornamentals). The reservoirs of the causative agents are weeds such as dandelion and field sow thistle. The disease is transmitted by various species of cicadas after the incubation period of the causative agent in their bodies and also by aphids. Yellows decrease the yields of greens, fruits, and seeds and impair the ornamental qualities of flowering plants. Some yellows (for example, cabbage yellows) are caused by fungi. The symptoms of these yellows are yellowing, wilting of leaves, and premature death of the plant. Control measures include crop rotation, cultivation of resistant varieties, removal of diseased plants, and control of weeds and disease carriers.

REFERENCES

Smith, K. Virusnye bolei.nl rastenii. Moscow, 1960. (Translated from English.)
Ryzhkov, V. L., and A. E. Protsenko. Atlas virusnykh bolcznei rastenii. Moscow, 1968.
Ploaie, P., R. G. Granados, and K. Maramorosch. “My coplasma-like Structures in Periwinkle Plants With Crimean Yellows, European Clover Dwarf, Stolbur, and Parastolbur.” Phytopathology, 1968, vol. 58, no. 8, p. 1063.

A. E. PROTSENKO

References in classic literature ?
As we talked we had been approaching the entrance to the cave, and as we crossed the threshold I ceased to wonder that the ancient green enemies of the yellow men had been halted by the horrors of that awful way.
"In the meantime," I continued, "I may discover some means of winning my way alone to the land of the yellow men, but if I am unsuccessful one life only will have been sacrificed.
Now that they were reunited, Dorothy and her friends spent a few happy days at the Yellow Castle, where they found everything they needed to make them comfortable.
"Valdez throw away yellow silk, and I take for my arrows so rain not wash off poison.
"Oh, Billina!" cried Dorothy, in a glad voice, and the yellow hen flew to her arms, to be hugged and petted by turns.
Dorothy sat right down in the road, the yellow hen in her arms, and began to stroke Billina's back.
Yellow Handkerchief came up to me in a familiar manner, the water in the cockpit slushing against his legs.
The spirit of the Chinese was broken, and so docile did they become that ere we made San Rafael they were out with the tow-rope, Yellow Handkerchief at the head of the line.
I have taken care in choosing my yellow plants to put down only those humble ones that are easily pleased and grateful for little, for my soil is by no means all that it might be, and to most plants the climate is rather trying.
It is dull work giving orders and trying to describe the bright visions of one's brain to a person who has no visions and no brain, and who thinks a yellow bed should be calceolarias edged with blue.
"How is my grammar?" asked the yellow hen, anxiously.
And, suddenly, while the cuckoo was sounding the half after midnight, a desperate clamour broke out in The Yellow Room.