Research projects archive

Research projects archive

HNS 196 - Identification of inoculum sources for the newly emerged Peronospora causing downy mildew on aquilegia

Start Date: 

Aquilegia downy mildew is caused by a species of Peronospora which is currently unnamed. The first occurrence of the disease appears to be on a nursery in 2011, with more widespread reports in gardens during 2013. Little or no work has been published on the disease and as a result it is difficult to establish from the literature why the disease has become more prevalent. This project aims to establish the main sources of inoculum for the disease on nurseries

PE 027 - Peppers: Review of options for control of aphid pests

Start Date: 

Integrated pest management (IPM) is commonly used by UK pepper growers to manage a range of pests. Aphids are potentially serious pests causing direct feeding damage and producing honeydew on which sooty moulds may develop. Effective control of aphid pests is difficult due to the pests ability to rapidly reproduce, widespread resistance in some species to important groups of insecticide, limited range of effective insecticide controls currently available to growers and hyperparasitism (secondary parasites attacking biological controls) disrupting biological control programmes.

Guided by practical IPM practitioners, this project will collate current knowledge on aphid biology and controls, including insecticides, biopesticides and biological controls. The review will draw on experiences, products and techniques used in other crops and in other countries. This will highlight opportunities for improving control of aphids in pepper crops specifically and in doing so provide a model that will inform control of aphid pests in other sectors.

PE 028 - Tuta absoluta: Investigating resistance to key insecticides and seeking alternative IPM compatible products

Start Date: 

This proposal has been prepared at the specific request of the TGA TC and the project leader is acting as a representative of that organisation.
Tuta absoluta arrived in the UK in 2009 and by 2012 was causing serious losses for some tomato growers. HDC projects PC302a-d developed a new IPM strategy based on the predator, Macrolophus pygmaeus, integrated with the IPM compatible insecticides, spinosad (Conserve) and chlorantraniliprole (Coragen). This was so successful that UK growers confess to having become complacent about the pest.
However, there have recently been several reports of control failures due to suspected resistance to spinosad. Furthermore, resistance to chlorantraniliprole has been confirmed in southern Europe. This project will investigate the UK control failures to determine whether they have been due to genuine insecticide resistance or to other factors. The project will draw upon the expertise of the Insecticide Resistance Team at Rothamsted Research who are world leaders in this field.
In addition, the team will search published literature and use existing contacts to list insecticides used to control Tuta absoluta and other leaf mining caterpillars in the Americas, Africa, southern Europe, Middle East and Far East, and identify those which could have potential within the UK tomato IPM programme.

PO 021 - Genetic and Environmental Interactions in Poinsettia Production and Shelf Life

Start Date: 

The UK poinsettia industry has had a high reliance on relatively few poinsettia varieties. The variety with the largest penetration is Infinity (c. 80% of the UK volume), followed by others such as Titan, Christmas Feeling, Prima, and Christmas Glory. The UK market tends to require slightly taller plants than the typical EU product, with clean red bract colours contrasting against dark green leaves. Prominent cyathia are frequently required, but without pollen.

There is now considerable interest in the use and exploitation of new varieties for the UK market. There are concerns that key varieties, which have been in the market for a number of years, are now starting to show non-typical or variable traits and habits. This may be due to issues with stock plant maintenance over a number of years.

A recent AHDB Horticulture Poinsettia growers study tour showed that plant breeders are actively working to breed new varieties or to develop improved stock management processes to “reboot and revamp” existing varieties. However, the number of new varieties entering the market is significant. These varieties are bred internationally, in particular in Europe, but not in the UK. The stock can be maintained in diverse areas such as Europe, Africa and Central America.

The process of variety selection by a grower is not simple. Growers will acquire insight from a number of sources, including own tests, visits to other growers, breeders and research stations, discussions with buyers, personal views regarding customer needs, extension services and documentary sources. Growers will also need to consider how a variety “fits” with their own facilities and production techniques. The process of variety selection is very expensive and time consuming, poor decision making can also have significant negative commercial consequences.

Improved and more effective decision making on variety selection can be established by understanding if there are significant grower x genetic interactions, ie do all varieties perform relatively the same on different holdings. If they do perform relatively the same on different holdings then it will suggest that varieties are relatively robust between growers. If there are significant interactions, ie varieties do not perform relatively the same between holdings, then variety decision making will be complex. If no interactions exist then variety selection might be made following the testing, on nursery, of relatively few varieties benchmarked to standard commercial controls. If interactions do exist then to make an effective decision it will require own on nursery tests of a very wide range of varieties, since it will never be clear how they perform until they are grown on a specific site.

Variety selection should also include an assessment of consumer performance. Shelf life trials are though difficult and costly to undertake at a grower level. Furthermore, a number of approaches to increase the resilience of the product post production are coming onto the market, these include the use of anti transpirant chemicals, small water absorbing plugs and the addition of “wick” water uptake mechanisms. These products have not been tested under controlled conditions to determine their efficacy.

PO 016a - The role of environmental factors in the incidence of Pansy mottle syndrome (PaMS)

Start Date: 


This proposal covers two elements of work; further monitoring on grower holdings in 2015 and Pansy sample testing for a virus potentially associated with PaMS. Continued monitoring will gather further evidence towards determining the triggers for PaMS (temperature, humidity, DLI, irrigation and production inputs and practices). The virus tests will confirm any association of Viola white distortion associated virus (VWDaV) with PaMS symptoms.

PE 026 - A study to review the scientific literature on the environmental risks of releasing non-native species of bumblebee (Bombus terrestris) for crop pollination

Start Date: 

Commercially reared bumblebees of the species Bombus terrestris are used for pollination of a number of UK crops. These commercial supplies of bumblebees are all produced outside of the UK. The sub-species used for commercial pollination include the British native subspecies B t audax, and two non-native subspecies: B t terrestris and Bt dalmatinus.
A recent change in policy from Natural England has resulted in withdrawal of permission to release the non-native sub-species for crop pollination. This has been driven by new evidence from the scientific literature reporting to show risks to wild bumblebees from diseases transmitted by commercial bumblebees.
However, these findings have been disputed by the UK Tomato Growers Association.
The aim of this proposal is to provide an independent review of the scientific literature relevant to the effects of releasing non-native sub-species of bumblebees as pollinators in the UK. This will provide the industry with a “second opinion” on the environmental risks associated with the release of non-native bumblebees. Any new information identified, gaps in knowledge, or concerns about the quality of scientific evidence could be fed into government policy making, helping to ensure that any decisions made by government regulators on the licencing of non-native bumblebees is done on the basis of the best available evidence.

HNS 187a - Evaluating the potential of plant growth regulators to limit plant growth on tree and hedging species

Start Date: 

Although widely used in other sectors, plant growth regulators are not currently applied to field grown tree and hedging species; a limited number of products (e.g. daminozide) have been tested by the industry (with limited success) prior to HDC project HNS 187. Undercutting is currently used as a means of limiting plant growth during the growing season. This technique cannot be carried out during periods of dry weather, as experienced during summer 2010 and 2011 in many parts of the UK. This project was designed to determine the ability of some chemical growth regulators to reduce the growth of deciduous field grown nursery stock during the growing season. The first year of the project (HNS 187) demonstrated that it was possible to limit the height of some key species (particularly Sorbus & Populus) through the use chemical plant growth regulators. The high rates of chlormequat used in year one of the trial generally resulted in useful height reductions however phytotoxic damage was unacceptable. In the second years trials (which were carried out in 2014) rates of plant growth regulators were reduced where necessary, to attempt to reduce phytotoxicity to an acceptable level whilst achieving the necessary growth control. Further reductions in rates and different timings are needed in some cases to strike the balance between achieving the desired amount of growth regulation whilst minimising crop damage to an acceptable level. Two additional growth regulators (Moddus & Cutaway) containing the same active (trinexapac ethyl) were included in 2014 trials. Both products were included because Moddus can be used on Forest nurseries under EAMU 2055/12. From past experience it was considered unlikely that the maximum permitted rate on the EAMU would achieve the desired growth regulation; this was proven in the trials carried out in 2014. Meanwhile three applications of Cutaway proved very useful on Sorbus, one of the five species tested – resulting in a near perfect crop. A further years’ work will allow us to build on the results to date, further fine tuning rates and timings. This should result in recommendations that UK growers can use in the future. Cutaway is not currently authorised for use on Forest nurseries or Ornamental plant production, however the results obtained in this project should help to support an EAMU for use in the aforementioned crops.

CP 134 - “eyeSpot” – leaf specific herbicide applicator for weed control in field vegetables

Start Date: 

Responding to concerns about loss of herbicides and pressure to target pesticides better and in lower doses, research will build on the expertise at Reading, Precision Farm Robotics and Knight Farm Machinery to develop a herbicide ejector which will apply metered droplets to leaves of unwanted plants.

CP 108 - AHDB Farm Scale Resource Use Efficiency Calculator

Start Date: 

AHDB wishes to build awareness and understanding in their stakeholder communities of the way that farm management decisions on the use of resources (including land) determine environmental impacts