Second year trials
First year trials
The second year trials for carrot and parsnips are aiming to identify suitable products to replace linuron, as well as follow up on positive treatments identified in the 2017 trials, including tank mixes and evaluating new treatments that have recently become available. There are 18 treatments, ten pre-emergence and eight post-emergence being tested. An open day was held on 27 June.
There are currently very few herbicide options for weed control for cucurbit and pumpkin growers. The limited range of herbicides leaves gaps in the weed control spectrum, and growers experience problems with a wide range of weeds including polygonum weeds, black nightshade, black bindweed, sowthistle, and a number of grass weeds.
The aim of the trial is to evaluate a range of herbicide treatments applied alone or in combination, and either pre or post planting to help fill some of the gaps.
An open day was held 16 July 2018 for growers and crop protection specialists to see how the 28 treatments in pumpkins and 26 treatments in courgettes have impacted weed growth and check for any negative impacts on the crop, images below.
The herbicide trials for herbs are continuing into the second year of the SCEPTREplus programme. Differences in crop damage between the six herb species and the various herbicides tested with useful crop safety data generated.
First Year Trials
Throughout the first year trials in 2017, weed control trials have been working to identify new control options for growers on a range of crops:
No crop damage observed at the end of flowering across the whole trial looking at replacement weed control options in Narcissus when applied during the dormant period.
The courgette herbicide trials are now complete. The results were presented at the Outdoor Cucurbits Growers Association meeting, 24 August 2017. You can view the presentation here.
Wing-P or Stomp Aqua applied inter-row in a tank-mix with Gamit 36 CS gave improved weed control compared to the current standard, was crop safe, and gave equivalent yields to the current standard
An application for an EAMU for Wing-P for inter-row use in courgettes has been submitted
AHDB9987 applied in a tank mix with Gamit 36 CS post-planting shows promise in controlling weeds in courgettes with no phytotoxic effects in this trial
AHDB9995 and Bonalan pre-planting followed by Gamit 36 CS were safe to the courgettes, but gave poor weed control of the weed species on site. Tank-mixing or being included in sequence with other products could improve the range of weed species controlled. Further work is needed to investigate possible safe product combinations
Further studies should also be repeated on the newer products Bonalan and AHDB9987
Herbicide trials, run by Fresh Produce Consultancy, examined weed control in celery. With the loss of linuron, weed control may be a challenge for celery growers and these trials aimed to help find some useful alternatives.
The treatments AHDB999, AHDB 9995 and AHDB 9974 all show promise in controlling weeds in celery. There is no single answer and a programmed approach will be required, further studies should be undertaken on AHDB999 including at the pre-planting stage
Gallery: Celery trials
Trials have been taking place at two sites in Rothwell, Leeds and Hampshire to look at the control of weeds in rhubarb, in particular Himalayan Balsam. There have been differences in control observed across the trials between the different treatments tested.
In Trial 1, a selection of 15 experimental post-emergence herbicide treatments have been applied after harvest and tested for crop safety and efficacy against a range of perennial and annual weeds present at the trial site.
In trial 2, recently approved product Callisto (mesotrione) has been applied at two timings post-harvest at three different rates and in tank mixes with currently approved products. This is to investigate crop safety and efficacy of this product at a post-harvest application timing.
Trials run by ADAS have been looking at crop safety in potted herbs for herbicide treatments. 10 different herb species are being used in the trials. Final assessments have been made on the first year trials and we will be taking forward several treatments for further trials. The first year results will be presented at the BHTA event on 30 November at Cranfield University.
Carrots and Parsnips
There were four trial sites for year one to investigate herbicide treatments for carrots and parsnips. The trials investigated options to replace linuron, as well as targeting groundsel, volunteer potatoes and mayweed species.
ADAS ran the trials.
The two parsnip trial sites were set up in the week commencing 8th May in Nottinghamshire and Suffolk.
26 Jun 17: Differences in crop safety and weed control at the Suffolk parsnip site are showing. See gallery below for images of the site taken five weeks after the crop was drilled and the pre-em applications sprayed. There are some clean plots but also differences in crop damage.
Gallery: Parsnip trials
Weed control trials for carrots started in May 2017, and pre-em treatments were reviewed in June 2017.
ADAS compared the effects of pre-emergence herbicide treatments on barley cover and carrots, with differences observed due to weather in Nottinghamshire and Suffolk. Both trial sites have light soils, but timing was difficult due to weather conditions. Heavy showers were experienced around the application period in Nottinghamshire and that has given greater effects on crops than in the East, which had light showers.
There are promising alternative products which could replace linuron in herbicide programmes and EAMU applications have been submitted. A number of products identified are however on the margins of crop safety, and further work is required to understand and guide growers now they can be used effectively to avoid commercially unacceptable levels of crop damage.
Gallery: carrot trials
Pre-emergence weed control for sweetcorn was a priority for SCEPTREplus trials. Control relies on very few post-emergence products and there is resistance risk from post- emergence products with ALS products.
Trials took place on two sites with typical key weed species that appear in the crop, but with different ranges of species at each site. We were therefore able to get greater information from the trials than at one site.
June 2017: Differences are starting to appear in the promising treatments and we continue to assess how these perform throughout the season to determine which of the products to raise as priorities to pursue.
- Stomp Aqua + Dual Gold was one of the best performing treatments at both sites and an EAMU (2834/17) has been secured for use on sweetcorn.
- Pre-emergence treatments AHDB9988, Stomp Aqua + AHDB9987 and Stomp Aqua + aclonifen show promise in controlling typical weeds in sweetcorn.
- Of the post-emergence applications AHDB9986 shows promise in controlling weeds in sweetcorn with no phytotoxic effects
- AHDB9988 gives a check to the crop when applied post-emergence but this may be commercially acceptable
- While AHDB9992 was one of the best performing pre-emergence products it now appears to be unlikely to be progressed to a UK approval
- Further studies should be undertaken on the newer products aclonifen and AHDB9987 to test how they perform in early season crops which are more sensitive and grown under temporary covers, as well as test how the most promising products perform in programmes.
Gallery: Sweetcorn trials