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Weber R.W.S.,Esteburg Obstbauzentrum Jork | Weber R.W.S.,University of Aarhus | Spath S.,Kompetenzzentrum Obstbau Bodensee | Buchleither S.,Kompetenzzentrum Obstbau Bodensee | Mayr U.,Kompetenzzentrum Obstbau Bodensee
Erwerbs-Obstbau | Year: 2016

Sooty blotch and flyspeck (SBFS) fungi colonise the surface of a range of fruits, especially apple, without penetrating the cuticle. Economic damage results from the exclusion of severely affected fruit batches from being marketed as table apples. A study of SBFS was conducted in 2007–2012 in the two largest German apple production areas, i.e. the Lake Constance and Lower Elbe regions. The absence of this disease complex from orchards under integrated pest management in both regions in all years was explained by the collateral effects of scab and storage-rot sprays with captan and quinone-outside inhibitors (QoI) such as trifloxystrobin. However, SBFS was economically relevant in organically managed orchards, being generally more severe in Southern Germany than in the North. In both regions, Peltaster cerophilus was the most frequently isolated SBFS fungus and was chiefly responsible for crop losses. Cyphellophora sessilis, Microcyclosporella mali and Schizothyrium pomi also contributed to SBFS in some organic orchards, whereas a diversity of additional species was confined to untreated orchards. Evidence was obtained that P. cerophilus overwinters within orchards, fruit mummies being one of presumably several colonised plant organs. Infections of young apple fruits were initiated at any time following the end of flowering, and P. cerophilus was capable of causing several infection cycles per season by means of conidial inoculum. The colonisation of sheets of waxed paper by P. cerophilus indicated that this species does not require fruit leachates for growth. No further expansion of colonies was observed during cold storage; instead, P. cerophilus was gradually displaced by other fungi. Differences in the susceptibility of apple varieties to P. cerophilus were due to fruit ripening, late-maturing cultivars being most heavily colonised, and to surface properties, varieties with a waxy bloom being conspicuously less strongly colonised than others. This fungus was unable to colonise russeted fruit areas. Repeated spray treatments with lime-sulphur and potassium bicarbonate throughout the season were effective and necessary to control SBFS in organic production. This strategy threatens the fungicide-saving potential offered by scab-resistant apple varieties. Cultural measures against SBFS include summer pruning as well as the manual removal of fruit mummies in winter. © 2016 Springer-Verlag Berlin Heidelberg

Faby R.,ESTEBURG Obstbauzentrum Jork
Acta Horticulturae | Year: 2014

The main fruit rot disease in strawberries is grey mould (Botrytis cinerea). Three-year trials were carried out in 2006-2008 to examine the influence of the floral stage (0, 20, 40, 60, 80 and a 100% blossom opening) and the frequency of applications during the flowering period (1, 2, 3, 4 and 5 sprays). The weather conditions showed large variations among the three years. 2006 was characterized by heavy rainfall during flowering and a dry harvest season. In 2007 the rainfall started in the middle of the flowering period and stayed until the end of harvest, with severe problems with Botrytis fruit rot in the commercial strawberry fields. In 2008 we had only some rain during flowering, but replicated rainfall during the harvest. Single applications had an effect against Botrytis at any time; however spraying at 60% flowering was most effective. In terms of application frequency, good results were achievable with as few as three sprays (25, 50 and 75% flowering). A sequence of four applications (20, 40, 60 and 80% flowering) gave only marginal further improvements to Botrytis control.

Faby R.,ESTEBURG Obstbauzentrum Jork | Ralfs J.-P.,ESTEBURG Obstbauzentrum Jork | Droge K.,ESTEBURG Obstbauzentrum Jork | Entrop A.-P.,ESTEBURG Obstbauzentrum Jork
Acta Horticulturae | Year: 2012

The main disease in raspberries is Botrytis fruit rot. For a good control, three or four treatments with chemicals during the flowering period are needed. A questionnaire in 2010 revealed that raspberry growers use a wide range of water volumes (300 to 1000 L/ha) and also apply with different nozzles, resulting in different drop sizes. In 2010 we started a project to optimize chemical treatments in raspberries. We compared the application of 300, 600 and 900 L water per hectare with coarse and fine drop size respectively. We measured the deposition of the chemicals on leaves and evaluated the biological efficacy against Botrytis fruit rot and two-spotted spider mites. The deposition trials showed more chemicals on the leaves with the lowest water volume (300 L) and with coarse drop size. There was no correlation between the deposition on the leaves and the control of Botrytis fruit rot and the spider mites. All treatments gave a good result in controlling Botrytis fruit rot, with no differences among the variants. The spider mites live on the bottom side of the leaves. None of the water treatments controlled spider mites efficiently. In further trials, we used a water volume of 1800 L per hectare and the air volume was increased from 25500 to 35800 m3/h; these trials were more efficacious.

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