A simulation program for the timing of fungicides to control Sooty Blotch in organic apple growing. First results in 2003

A simulation program for infections by Sooty Blotch was developed based on literature data and expert judgements. The value of the model as tool for timing fungicide sprays to control Sooty Blotch was tested in 2003 in two randomized plot trials, and four “on farm” trials where the treatments where made by the growers. Disease pressure was relative low due to the warm and dry summer of 2003. Two to five post infection treatments with lime sulfur or coconut soap aimed at severe infection periods as indicated by the model provides 72 to 100 % control

Observations on the epidemiology of Sooty Blotch in Organic orchards in the Netherlands

From 2002 to 2005 field observations where made on the occurrence of Sooty Blotch (SB) in unsprayed orchards on the apple variety Topaz. First SB symptoms in high inoculum orchards where found after on average 639 leaf wetness hours following the first rain 10 days after petal fall. Even then symptoms where present only on places on the fruits that probably stayed wet longer than the leaf wetness sensors have indicated. Weather stations that are set up to register average orchard conditions are unlikely to detect the wetness conditions that lead to SB infections in critical parts of the orchard. From the delayed symptom development compared to the published data form USA we concluded that un-der Dutch conditions the lower temperature retards the symptom development. In the first month after the first symptoms where found disease progress was slow, but increased towards the harvest. The gradual increase of both disease incidence and severity, and the appearance of the symp-toms suggest ongoing new infections on the fruits during summer rather than one major SB infection that spreads on the fruit. Within a year the disease incidence between orchards varied form 0 to over 90%, but between years the disease incidence in an individual orchard stayed in the same range. This makes disease history an impor-tant factor in the panning of a control strategy

Evaluation of grapefruit seed extract as natural fungicide to control apple scab in organic apple growing

C-pro, an experimental fungicide based on grapefruit seed extract was compared to copper oxychloride for the control of apple scab in a field trial. Efficacy and possible phytotoxic effects where accessed. The C-pro formulation was analysed for possible chemical additives by HPTLC. C-pro proved tot be more effective in controlling apple scab then the standard rate of 300 gram copper oxychloride per ha, and gave a better leaf quality and less fruit skin russeting then the standard program of copper oxychloride. However C-pro contained 6.6 % of the synthetic preservation agent benzethonium chloride what excludes C-pro from use in organic agriculture. There is a growing interest in grapefruit seed extract products as well as in other plant extracts as potential crop protection materials. To prevent disappointments and waist of resources it is necessary to analyse these materials on possible chemical additives before taking them into efficacy trials

Resistance management in Vf apple scab resistant organic apple orchards

Modern Vf scab resistant apple varieties open the way for organic growers to lower fungicide input, higher yields, better skin quality, more biological control for mites and insect pests and better consumer acceptance of their management practices. Manny examples in the past years have shown however that the Vf resis-tance can be easily overcome by local scab populations in north-western Europe. Discussions during the meetings of the IOBC working group Diseases in Orchards in 2000 in Fontevraud (France) and in 2003 in Lindau (Germany) lead to a set of management practises necessary to prevent gene-fulx, and selection to-wards Vf virulence in the local apple scab populations. Eleven orchards of the Vf resistant apple variety Santana that where planted between 1998 and 2000 where monitored for apple scab lesions on fruits form 2002 to 2005. The results where evaluated in respect tot the applied resistance management practices. We conclude that fungicide treatments on the major primary scab infections are the key factor in the resistance management on Vf resistant apple varieties. From a practical viewpoint these early season fungicide applications are also necessary for the control of powdery mildew, as the main Vf- resistant apple cultivars appear to be relatively susceptible to powdery mildew. For private gardens apple varieties with field resistance to apple scab should be advised, not Vf resistant varieties

Disease management in organic apple orchards is more than applying the right product at the correct time

The relative importance of diseases on apple is varying with cultivar, management, time, and climate. Many aspects of the cropping system influence the development of diseases. The choice of the variety determines the disease management during the lifetime of the orchard. Cultural practices improve the growth and nutrial status of the tree, and therewith influence the susceptibility of the plant and fruits to diseases directly. Prolonged growth can also have an indirect effect by causing a microclimate and growing pattern that favours infection of tree, leafs and fruits by various diseases. Sanitation measures are common practise for most organic fruit growers and help to make other measures more effective by reducing infection inoculums. Despite all preventive measures, disease control in organic orchards at an economically feasible level still largely depends on the application of fungicides. Measures that allow reduction of fungicidal applications on key diseases, lead to the development of a secondary disease complex that can cause severe losses when not managed effectively and make a well thought-out control strategy necessary. In research, advisory and practical decision making, disease management in organic orchards should always be seen in the perspective of the management of the total growing system. With all factors that contribute to disease management in organic orchards optimized, we are able to successfully implement new materials and methods that may not be as effective as common fungicides in themselves, but add to the effectiveness of the disease management system as a whole. This total system approach makes organic fruit growing what it is

A new system to evaluate Organic Inputs in EU. How does if affect the grower

Conclusions (1) What can be solved: - Possibly quicker - More transparent, technical and objective evaluation that allows for development What can not be solved: - Differences between countries due to lack of active policy for local registration of Organic Inputs Conclusions (2) What should be considered System effects in: - “domino” effects in the use of other PPP” - substitution of PPP’s - preventing resistance - moving organic production to geographical areas where more Inputs are allowed Conclusions (3) A transparent, technical and system-based evaluation of input materials, aimed at further and equal development of organic agriculture in all EU member states would be highly welcome

The post infection use of Lime sulphur to control apple scab. Experiences in the Netherlands 1999-2002

Until yet the fongicides in organic fruit growing (sulphur, lime sulphur, copper, claypowders) are used as protectants applied before the rain, or as stop-spray or during infection development. Post infection use of lime sulphur could reduce the number of spray rounds, allowing for the use of less pesticides, and reducing the adverse effect on beneficial insects and mites. In the 30's of the last century, post-infection effects of lime sulphur were found in lab and field trials. Effective control was achieved by applications 30 to even 72 hours after the start of rain. Field trials in the Netherlands in 1999, 2000 and 2001 confirmed that post-infection applications of lime sulphur are effective under field conditions till at least 20 hours after the start of the infection. Evaluation of the practical experiences with the use of lime sulphur as post-infection spray in 2000 and 2001 however showed that a dose of at least 0,15 % should be used, and the product should be applied with a high water volume, or on wet leaves to allow for an effective contact between the pentasulphides and the fungus. In 2000 one application of lime sulphur two weeks after blossom lead to severe russeting of the fruit skin on the variety Jonagold

Diplodia seriata, cause of black fruit rot in organically grown apples in Holland, Belgium and Northern Germany

A fruit rot resembling Gloeosporium infections but appearing on fruits prior to harvest was noticed in organic apple orchards in Holland, Belgium and Northern Germany in 2007. Infections were most commonly observed on ‘Elstar’, but other cultivars were also affected. Fruit colonisation progressed in two steps, whereby a latent stage of sunken black lesions in immature fruits gave rise to a rapidly spreading firm brown rot upon fruit ripening. Isolation experiments from both stages consistently yielded a single species of fungus identified as Diplodia seriata, formerly known under the teleomorph name Botryosphaeria obtusa. Lesions of D. seriata were also seen on leaves as necrotic light brown spots surrounded by a purple halo, and occasionally on small twigs as cankers. Fruit mummies on apple twigs were heavily colonised by D. seriata and are thus likely to carry inoculum for fruit infections during late summer or in the following growing season

CO-FREE Alternative Test Products for Copper Reduction in Agriculture

The project CO-FREE (2012-2016) aimed to develop strategies to replace/reduce copper use in organic, integrated and conventional farming. CO-FREE alternative test products (CTPs) were tested and integrated together with decision support systems, disease-tolerant varieties, and innovative breeding goals (ideotypes) into improved management strategies. CO-FREE focused on apple/apple scab (Venturia inaequalis), grape/downy mildew (Plasmopara viticola), and tomato and potato/late blight (Phytophthora infestans). Starting point of the project were ten CTPs with direct or indirect modes of action including Trichoderma atroviride SC1 and protein extract SCNB, Lysobacter spp., yeast-based derivatives, Cladosporium cladosporioides H39, the oligosaccharidic complex COS-OGA, Aneurinibacillus migulanus and Xenorhabdus bovienii, sage (Salvia officinalis) extract, liquorice (Glycyrrhiza glabra) extract, PLEX- and seaweed plant extracts. As the project progressed, further promising CTPs were included by the partners. Field trials were performed in different European countries in 2012-2015 following EPPO standards. In the first years, stand-alone applications of CTPs were tested. In the following years these were integrated into complete strategies. Effects on main and further diseases, on yield and on non-target organisms were assessed. Here, field trial results with CTPs are summarized