Plant Establishment and growth
A beet plant is said to be established when it has six true-leaves and is therefore likely to survive until harvest. The number of these plants per 100 seed positions is the plant establishment percentage.
To calculate establishment percentage:
. Count the number of plants in several randomly selected 20m lengths of row. Using a 20m length of string anchored to a stick or cane will be more accurate than trying to pace out 20m.
. Multiply the number of plants in each length by the seed spacing in centimetres and divide by 20.
. Investigate what has gone wrong if many of these results fall below 70%
Growth is still relatively slow but earlier drilled crops are now looking better with 6 -8 true leaves on fertile sites.
Nutrition
Manganese deficiency is showing up in some crops and foliar sprays should be applied when conditions allow.
Where second and final nitrogen applications are still required these should be applied as soon as conditions allow. See Advisory Bulletins No. 10 and 11 for further information.
Herbicides
Recently applied herbicides are working exceptionally well, although some reports of slight crop effects from triflusulfuron methyl (e.g. Debut) which has given rise to some yellowing of the beet.
FAR programmes are also working well - even with longer gaps than usual, the number of applications range from 4 on mineral soils up to 6 on the organic ones.
Control of volunteer potatoes (see Advisory Bulletin No. 10), and thistles is required in fields where these are a known problem, programmes should be based around clopyralid. To control annual sow-thistles apply clopyralid at the 2 true leaf of the weed.
For optimum control of creeping thistles a sequence of clopyralid applications is the most appropriate approach. The first application should be made when the weeds are at the rosette growth stage, followed by a second application three to four weeks later, it is likely that applications of clopyralid will be part of a sequential low dose program in 80 to 100 litres of water with tank mix partners. One creeping thistle stem per square metre can reduce the yield of sugar beet by one tonne per hectare.
Blackgrass is still emerging, allow sufficient intervals between other herbicides to ensure active growth of the weed where using graminicides.
Weed beet
Weed beet multiply diseases such as rhizomania, downy mildew an d just one weed beet square metre can reduce yields by 10%.
Tractor hoeing before weed beet reach the four leaf stage is very effective in removing up to 70% of weed beet (i.e. those between the rows). In some situations two passes of the tractor hoe may be required. Remember that hand pulling later in the season is not feasible if you have more than 1,000 weed beet/ha, so it is advisable to start planning options for weed beet control from the start of the season.
Mangold fly - leaf miner (Pegoma hyoscyami)
Mangold fly eggs are now being found on the underside of sugar beet leaves (Photo 1), they are approximately 1mm long and usually found in groups of 2-10. Following hatching the larvae which are legless, without a clearly defined head and about 6-8 mm long burrow into the leaves and live between the upper and lower surfaces (Photo 2). Whe n fully fed the larvae exit the leaves and pupate in the soil where they overwinter. There are usually 2 - 3 generations per year, or more as we experienced last season. Early attacks on slow growing small backward plants can cause economic losses through direct feeding damage, and can also make the sugar beet plants more susceptible to adverse herbicide affects.
Generally the new generation of insecticide seed treatments will give effective and reliable protection against leaf miner damage for about 10 weeks after drilling. This season because of the cold conditions and high rainfall growth of many crops has been much slower than is normal and as a result some crops are now vulnerable to attack and may require a foliar insecticide at egg hatch see table 1.
Treatment thresh old is:- "When the number of un hatched eggs in combination with viable larvae exceeds the square of the number of true leaves."
For example a plant with 4 true leaves would require a population of 16 eggs and larvae before treatment is justified.
Aphids - Myzus persicae
With many crops having now been in the ground over ten weeks in some cases it is possible that crops may not achieve maturity resistance to aphid attack (12 leaf) before the protection from the seed treatments is exhausted.
Aphid activity and the potential transmission of viruses is of particular concern with the high number of resistant aphids in the population. Area managers and independent advisers are requested to send samples of any aphids that they find on sugar beet to Brooms Bar n for analysis.
Steps are in place to seek approval for additional pesticides to control aphids in the crop via a SOLAR (Specific off-label recommendation), to ensure that should these products be required they can be used legally. This approval has not yet been gained and details of any approval will be circulated once achieved.
BBRO Open Days - all open days will be between 12.00 and 3.00pm
The BBRO are pleased to announce the 2012 programme of field Open Days. These open days set out to provide technical assistance and advice from the very latest research findings to help you get the most from your sugar beet crop.
In addition to the technical presentations in the field, each event will feature a large number of trade exhibits and the opportunity to meet with a range of industry experts.
As in previous years, there is a no charge for attending any of these events and BASIS & NRoSO points will be available on each day, as well refreshments.
They will be four events for 2012, dates and locations are as folllows:
Newark - Tuesday 22nd May - East Mere House, Mere Road, Bracebridge Heath, Lincoln, LN4 2JB
Wissington - Thursday 24th May - Top Farm, Holbeach Hurn, Spalding, Lincolnshire, PE12 8LW
Cantley - Wednesday 30th May - Hall Farm, Reedham, Norwich, Norfolk, NR13 3HW
Bury St Edmunds - Thursday 31st May - Broom's Barn, Higham, Bury St Edmunds, Suffolk, IP28 6NP
Details of the events, including directions, are available on the Sugar Beet Portal (www.uksugarbeet.co.uk)
BASIS points
Two BASIS points in total (not per bulletin) have been allocated for the period between 01/06/11 and 31/05/12 reference CPD/20108/1112/a. In order to claim these points please contact Jill at BASIS registration on Jill@basis-reg.co.uk
For technical queries contact the BBRO helplines:
Pam Chambers , pam.chambers@rothamsted.ac.uk 07887 628357
Colin Walters colin.walters@britishsugar.com 01733 422088
Caution : this information is based on results of experiments and experience but cannot constitute a recommendation.
No comments have been made.