SCEPTRE WEEDS GROUP MEETING – ADAS, Battlegate Road, Boxworth, Cambs, CB23 4NN

(Tel. 01954 267666) - 7th September 2012

Attending: A Richardson, S Jackson, C Knott, J Atwood, L Tatnell, H. Williams, V. Powell, D. Picccaver. Roma Gwynn attended via conference call.

Apologies - W Brough & T. O’Neill.

Fruit – Year 2 results

E 2.6 Strawberry: Evaluation of residual herbicides - Herbicides applied in March as strawberries were just coming out of dormancy (traditional crop, already established), UTC but no commercial standard. Primary focus was to investigate phytotoxicity because 2011 had highlighted possible issues when two treatments. Weed levels were low in the trial and no significant differences were recorded between the UTC and the treatments. One trial treatment showed a significant yield reduction and phytotoxicity was quite extreme (more severe than last year). All other treatments were relatively safe so could be pursued dependent on availability and ease of acquiring EAMU’s.

E2.7 Perennial weed control on bush and cane fruit – Herbicide trials were undertaken this year to study : Thistle and nettle control in blackcurrants and phytotoxicity in raspberries. Treatments were applied in March in two ways, firstly as direct spray beside the base of bush, and secondly across the lower part of the bush. The same treatments were applied across all 3 trials. Good control of nettles was recorded from 2 of the trial products and on blackcurrants all treatments were safe except for one trial product. In raspberries one trial product showed bad leaf deformation ruling it out of further trials, other treatments appeared relatively crop safe.

E2.9 Electrical weed control – Trials were undertaken in 2012 using a tractor mounted prototype. Trials consisted of one voltage (half power 7KVa) but at variable speeds and were undertaken between the rows of a blackcurrant crop. A hand-held probe was also tested to investigate the effect of treatment close to the crop. Treated areas were assessed one week after treatment. Excellent control of thistles was achieved across all speeds but weeds have to be in contact therefore the machine set up is crucial. Overall control was good considering the significantly wetter year. An area of docks tested from last year had not re-emerged this year. The effect on nettles was less encouraging, instant knock-down was observed but quick regrowth followed.

Field Vegetables – Year 2 results

E1.9 Solutions to the loss of active ingredients for weed control - Two herbicide products were trialled over a range of crops. These products have been tested previously pre-emergence. The trial site was a on light silt at Elsoms as in previous years. As the site experienced heavy rainfall treatments were likely to work well and phytotoxicity risk would also be high. Weed emergence was very high across the plots yielding good data.

One trial product was safe on carrot, parsnip and coriander. It was also safe on onion and leek at 1TL and celery post-transplanting. However it was NOT safe to peas, broad beans, dwarf French bean (however is safe on these crops pre-emergence). Product is not safe on brassicas or lettuce pre or post emergence. This product gave excellent control of small nettle.

The second trial product was applied at lower dose rates than pre-emergence doses. It causes yellowing and stunting. This product is safe on lettuce (Challenge iceberg cultivar) and legumes post-emergence. It was not safe on other crops. This product gave excellent control of knotgrass and redshank at very low dose rates and also suppressed volunteer potatoes.

E1.10 Precision application of residual herbicides to improve crop safety/weed control (band spraying) - Work this year used a machine with two sets of even spray nozzles each attached to different tanks to apply different products both between crop rows and over the top of the crop row. All treatments applied to both brassicas and alliums were approved. Trials were undertaken on a range of soil types for the onions. All brassica trials were on silt soils due to delayed planting this year. Treatments were applied after sowing in March and control was assessed in May on all soil types. Weed pressure was very high at 3 out of the 4 trial sites. In onions little phytotoxicity was seen when using high rates of residual herbicides close to but not over the planted row. As expected higher rates of residual herbicides resulted in better weed control. In brassicas use of over the row applications of metazachlor in conjunction with in-row applications of other residual herbicides resulted in significantly less crop phytotoxicity without any reduction in weed control.

E1.11 Weed seed germination enhancers

Pot screen trials undertaken in glasshouse conditions with a range of annuals and oilseed rape using ‘Smokey Water’. The treatments consisted of 3 reps. Applications were applied within 24 hours of sowing. No differences were observed with OSR or any other weed except chickweed, which did show an enhanced effect. Overall the results were variable initially and over time the treatments had caught up in 3-4 days.

E1.12 & E2.8 Evaluating bio-herbicides

The purpose of this work was to evaluate the efficacy of novel bio-herbicides compared to conventional products for the control of perennial and annual weeds, the work also studies the control of strawberry runners. Perennials were taken from rootstock for the trials and annuals were established from seed. Runners purchased as runners. Each treatment had 4 reps. The herbicides were applied to perennials at 1-2 leaves emerging stage, annuals at 2-3 leaves. Runners were sprayed 3 weeks after planting. Two replicates were re-treated after three weeks for the perennials and strawberry runners only. One bio-herbicide product showed good efficacy on some weed species, however perennial weeds showed very quick regrowth after treatment.

E1.13 Demonstration of a novel tractor mounted electrical treatment for control of annual weeds - This equipment was demonstrated at the SCEPTRE Weeds Open Day held at Elsoms in June 2012. A shrouded electrode was run between rows of cauliflower to demonstrate the potential for inter-row weed control.

Any Other Business

Coding was raised as an issue. Projects should provide product names where possible so growers can see progress. There is however a need to get permissions in writing from companies from authorised personnel before publishing names – to be discussed further at the next PMM meeting on 30th October 2012.

Date of next meeting – Friday 7th December 2012. 10am – Allium & Brassica Centre, Kirton, Lincolnshire.