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In 2016 a greenhouse scenario for soil-bound crops has been adopted in the Dutch authorisation procedure for plant protection products to assess the exposure of aquatic organisms. However, two important shortcomings resulting from the parameterisation of the surface water scenario were discovered. These were due to the assumption of an exact repetition of the irrigation scheme for a fully-grown chrysanthemum crop and that of a top layer with a well-developed macropore system. The first assumption resulted in an extreme sensitivity of the exposure concentration to the application date and the second assumptions was considered unrealistic, because the soil in the greenhouse is frequently ploughed. The above two issues were addressed in the revised exposure scenario presented in this report. The first important improvement was the division of the greenhouse into 24 cultivation sections with a description of the sequence and growth development of all crop cycles in each cultivation section. The second shortcoming was remedied by the change of the topsoil layer with a well-developed macropore system into a topsoil layer without macropores. The target concentration for the assessment of the exposure in surface water strongly depends on the half-life of the substance in the greenhouse soil. Should data on the DegT50 obtained from measurements in greenhouse soils not be available, we recommend to apply provisionally the same factor as included in the tiered assessment scheme proposed by Wipfler et al. (2014), i.e. multiplying the DegT50 value derived from measurements in field soils by a factor 10. The new version of the Greenhouse Emission model (GEM) contains the option to specify an application day relative to the date of planting or harvest. If the GAP (Good Agricultural Practice) of a plant protection product specifies a number of applications per crop cycle, this option should be used. If the GAP specifies a number of applications per year, the application option to specify an absolute date should be selected. For the selection of the application date resulting in the required percentile of the PEC90 in surface water, we recommend an update of the SAFE (Select Application For Evaluation) tool. Suggestions are made to increase the validation status of the model and for the further development and use of the GEM model within the EU.

This project aims to develop a sustainable system approach for fruit rot problems in vegetables based on plant resilience and integrated pest management (IPM). This project was contributed by Top sector Horticulture & Breeding, Dutch Produce Association, Dutch Horticultural Board, Biobest Group N.V.and Horti Nova B.V. In the first three years of the project laboratory, greenhouse and field trials were performed. The results of this project confirmed that a multiple approach is most effective and a single treatment is not sufficient enough. The use of biological antagonists was one of the most effective measures to protect the flowers against fruit rot. Greenhouse trials with plant hormones indicate that sensitivity of a crop to fruit rot is affected by increased jasmonic acid/ethylene production. The infection process can be inhibited by climate measures when flowers are exposed to high relative humidity and protected from high radiation. The temperature seems to have less influence. The irradiation has a strong effect on the crop which is measurable in a changed composition of plant sap analyses and sap flow movement in the plant. Different screening strategies appear to have little influence on the sap flow movement. The research in the fourth year focused on further development of an early monitoring system through the detection of Fusarium in young fruits and improvement of biological control under commercial greenhouse conditions in The Netherlands. Dit project heeft als doel om een duurzame systeemaanpak te ontwikkelen voor vruchtrotproblemen in de glasgroenteteelt gebaseerd op plantweerbaarheid en Integrated Pest Management (IPM). Aan dit project is bijgedragen door Topsector Tuinbouw & Uitgangsmaterialen, Dutch Produce Association, Productschap Tuinbouw, Biobest Group N.V. en Horti Nova B.V. In de eerste drie projectjaren zijn zowel laboratorium-, kas- als praktijkproeven uitgevoerd. De resultaten van dit project bevestigen dat uitval door vruchtrot niet met één maatregel is te voorkomen, maar een nauw samenspel van meerdere maatregelen vergt. De inzet van biologische antagonisten is één van de effectieve maatregelen om bloemen preventief te beschermen en kasproeven met plantenhormonen geven aan dat (ras)gevoeligheid voor vruchtrot sterk beïnvloedt wordt door een verhoogde jasmonzuur/ethyleen productie. Via het klimaat kan het infectieproces geremd worden door bloemen bloot te stellen aan hoge relatieve luchtvochtigheden en bescherming tegen hoge instraling. De temperatuur lijkt het minst van invloed. Het effect van een hoge instraling was meetbaar middels plantsapanalyses en via de sapstroomsnelheid van een plant. Verschillende schermstrategieën hebben weinig invloed op de sapstroom. Het onderzoek in het vierde jaar heeft zich gericht op de verdere ontwikkeling van een vroegtijdige monitoring middels de detectie van Fusarium in jonge vruchtbeginsels en bestudering van de overbrenging onder praktijkcondities van antagonisten.

In de jaren negentig is het recept voor de voeding bij tomaat in recirculatie ontwikkeld. Inmiddels zijn we ruim 25 jaar verder. De teelt heeft een enorme ontwikkeling doorgemaakt; tijd om de voeding bij tomaat tegen het licht te houden.

Plantsapanalyse rukt op als instrument om de bemesting af te stemmen op de behoeften van het gewas. De techniek heeft zijn nuttige kanten, maar er zijn ook zwakke schakels. De belangrijkste is dat goede streefwaardes voor alle omstandigheden ontbreken. Voor sommige elementen kan de analyse toegevoegde waarden hebben, voor andere helemaal niet.

In soil-less culture systems Fe is usually supplied as chelate to ensure an adequate availability of this element. As chelates have affinity for many metal ions these chelates will interact with other cation nutrients in nutrient solutions. This affects the availability of Fe and other nutrients. The effects of Fe-chelate types, pH, and Zn concentrations on the availability of Fe, Zn and other micro nutrients in the nutrient solution were tested with rock wool grown cucumber as test crop. In the first experiment the Fe-chelates DTPA, EDDHA and HEEDTA (25 μmol L-1) and Zn target values of 5, 25 and 50 μmol L-1 in the root environment were compared. In the second experiment DTPA and EDDHA and Zn target values of 5 and 50 μmol L-1 at two pH ranges: 5-5.5 and 6.0-6.5 were compared. No yield nor fruit quality were significant affected in both trials. Chlorosis occurred severely at the high pH levels but was not significantly different among the chelate- or Zn treatments Necrosis of leaf margin occurred with the DTPA treatments, specifically at high pH. The required Fe-chelate dosage to keep the target levels of Fe was much higher for HEEDTA than for DTPA and EDDHA, at high pH a higher dose of DTPA was needed than for EDDHA in particular with increasing Zn levels. The Fe uptake was not significantly affected by the treatments. The Zn uptake increased with the supply. Interaction of chelate type and pH was found. With EDDHA the Zn uptake was three to five times higher than with DTPA and HEEDTA at high pH. This was in line with the much higher Zn supply needed with EDDHA at high pH The results of these experiments draw the attention to the effects of different Fe chelates on the availability of several micro nutrients to plants, which apparently can be explained by a different behavior to complexation.