Yellowing/reddening syndrom of parsley (Petroselinum crispum (Mill.) Nyman ex. A.W. Hill): results of the research carried out in 1993 [in Belgium]
1994
Bleyaert, P. (Provinciaal Onderzoek- en Voorlichtingscentrum voor Landen Tuinbouw, Roeselare (Belgium))
An experiment with parsley planted out in April 1993 [in Belgium] compared the effect on leaf reddening of covering with insect nettings of various mesh sizes, frequent treatments of pirimicarb plus lambda-cyhalothrin and frequent treatments of propamocarb. Plants covered with insects nettings showed a clear relationship between the number of plants with leaf reddening and the number of aphids per plant, thus offering new evidence for carrot motley dwarf disease being the cause of the coloration phenomenon. While fine meshes (0.5 mm and 0.6 mm) could prevent aphid intrusion and thus leaf reddening - almost totally, large meshes (1.6 mm) allowed more aphids to intrude, resulting in more leaf reddening. Because of the retardation of aphid intrusion however in comparison to control, even the insect nettings with large meshes - being much cheaper than the former ones offered a sufficient extent of protection to leaf reddening. Contrary to pirimicarb, the mixture of pirimicarb plus lambda-cyhalothrin could reduce the degree of leaf reddening to a level that was economically acceptable. This effect possibly is the result of a repellent action of lambda-cyhalothrin. The use of the fungicide propamocarb did not yield any effect.
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