What Is Aster Yellow Sickness?

Aster yellow sickness (ALD) is a fungal infection which affects the leaves of many vegetables including carrots, turnips, parsnip, celery and other members of the Brassica family. Alder trees are also affected by this disease. The cause of ALD is not known but it appears to be transmitted from aphids or thrips. The fungus causes lesions on the leaves called albedo spots (see picture). These spots are brownish-red and appear on the upper surface of the leaves. They may resemble small sunburns. The albedo spots usually disappear within one to two weeks but they do not necessarily mean that the plant is cured of ALD.

Symptoms Of Aster Yellow Sickness:

The first symptom of ALD is loss of color in the lower part of the leaves. After the albedo spots disappear, the plants may show other symptoms such as wilting, browning and death. The plant will eventually die if left untreated.

Control Of Aster Yellow Sickness:

There are several methods to control this disease. One method is to spray the affected area with insecticidal soap or steam at high pressure for five minutes every day until all signs of ALD have disappeared. Another method is to remove and dispose of all infected plants.

Aster Yellows Disease On Carrots:

Aster yellows disease on carrots is caused by the same fungus that causes ALD in other members of the brassica family. This disease is common in the northeastern and north—central United States. Some states such as New York, Pennsylvania, Connecticut, and Minnesota report high losses due to this disease.

This disease is most commonly found in gardens that have sandy soil.

Sources & references used in this article:

Remission of aster yellows disease by antibiotics by RE Davis, RF Whitcomb, RL Steere – Science, 1968 – science.sciencemag.org

A genotype-based system for identification and classification of mycoplasmalike organisms(MLOs) in the aster yellows MLO strain cluster. by IM Lee, RE Davis, T Chen, LN Chiykowski, J Fletcher… – Phytopathology, 1992 – apsnet.org

‘Candidatus Phytoplasma asteris’, a novel phytoplasma taxon associated with aster yellows and related diseases by IM Lee, DE Gundersen-Rindal… – … of systematic and …, 2004 – microbiologyresearch.org

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