NEW INVESTIGATIONS ON FACTORS CAUSING GUMMOSIS IN APRICOTS

M. Heimann
The apoplexy of apricots is a complex aspect of disease caused by various external and internal factors. Most important of these are: damages due to frost and cold weather, inadequate conditions of location and a water surplus caused by insufficient draining of soil moisture; also a lack of affinity of the combination partners, an inadequate and proliferous subsoil as well as derangement of nutrition. In addition parasitic fungi, such as Verticillium alboatrum, Monilia laxa, Valsa sp., Armillaria mellea and others many also contribute to producing apoplectic symptoms.

As an example of the significance of lacking affinity among combination partners and of water surplus due to insufficient draining of soil moisture causing the disease we are discussing below the following tests. In two test plantations at Oppenheim/Rhein the disposition of apricots to contract the disease was tested in 7 combinations, and at Ingelheim/Rhein in 12 combinations. Figures 1 to 3 show the course of the disease in an apricot plantation planted at Oppenheim in 1959. As combination partners there were in that plantation:

»Kriechenflaume« + »Mombacher Frühe«

»Brompton + »Mombacher Frühe«

»Marunke« + »Mombacher frühe«

»St. Julienpflaume« + »Momnacher frühe«

»Kriechenpflaume« + »Kecske, Frühe«

The test was carried out with 6 trees per plot repeated four times. Type of soil: deep, sandy loam-soil. The first classification in that plantation took place in September 1964. On that occasion already very clear differences in the behaviour of the individual grafting partners resulted (Fig. 1). The combination »Kriechenflaume« and »Mombacher« showed a relatively and good compatibility (plot No. 1). Out of a total of 24 trees, which were all in their fifth year, 19 were healthy and 2 had got the disease, 3 had died and had been replaced by new ones of the same combination. The partners »Brompton« — »Mombacher« (plot No. 2) were less well compatible. Although 18 of the originally planted trees looked healthy, 5 of the others had died and had been replaced by others of which again one had got the disease. The third combination »Muranke« — »Mombacher« (plot No. 3) showed a high degree of incompatibility. Only one of the trees planted in 1959 still looked healthy, 5 were partly or heavily infected, 18 had died and been replaced by new ones; and of those again 4 trees showed slight to heavy symptoms of the disease,

Heimann, M. (1968). NEW INVESTIGATIONS ON FACTORS CAUSING GUMMOSIS IN APRICOTS. Acta Hortic. 11, 529-542
DOI: 10.17660/ActaHortic.1968.11.53
https://doi.org/10.17660/ActaHortic.1968.11.53

Acta Horticulturae