April Cropnotes 2012.
I recorded 41mm (1.6”) of rain in March, and with the last fortnight being both warm and dry there have been good opportunities for spring drilling. At the time of writing the weather seems settled into its current pattern and concerns about another spring drought are mounting.
Yellow and brown rust have been widely reported during March, but with T0 sprays going onto crops now we should see both diseases quieten down. Monitoring spray intervals will be important in rusty varieties as with a lot of fresh leaf growth emerging after treatment even the most persistent products will not provide much more than 3 weeks protection.
Barley yellow dwarf virus has become visible even in some crops that were sprayed twice last autumn. It can be distinguished from the soil borne virus barley yellow mosaic as the patches of the latter condition are characteristically kite shaped and there is yellow flecking within the youngest leaves.
Oilseed rape: The first crops are just into yellow bud. Pollen beetle have been seen as temperatures rose last month. Spraying with Pyrethroids should be avoided if possible to avoid selecting for resistance. Biscaya, Rumo and Plenum have approval for this problem now, but are more expensive. Crops should be monitored until the start of flowering. Thresholds are quite high for the winter crop at 10 to 15 per plant across the field; not just the headlands.
Sclerotinia has been much more widespread in the last 3 seasons, so we should plan to apply at least one prophylactic spray this year at mid flowering. On forward well established crops a yellow bud PGR fungicide will have a useful additional effect on Sclerotinia suppression. The main options for Sclerotinia control are, Filan, Proline 275/Prosaro, Amistar and Compass. Expect about 3 weeks persistence from one application.
Peas & Beans: Weevil have been evident in both winter and spring bean crops in the last 10 days and pyrethroid sprays should be going on to limit activity.
Thrips can cause problems in the growing points of some crops, so take time to inspect emerging crops and treat with a pyrethroid especially if growth is slow.
Chocolate spot has been visible in winter bean crops where winter frosts caused some tissue damage. Treatment should not be required until the disease moves onto new growth..
Bravo 500 no longer has approval for use in beans or peas. It is approved in the co-form Alto Elite/ SAN 703.
Sugar Beet: Most of the beet crop has been drilled into good seed beds, so there is every reason to expect a regular emergence in the next few days. To date mice damage has been at very low levels, but this can change for the later drillings if they get a taste for the seed from spills etc.
There is now a limit of 960g/ha total dose per crop for Phenmedipham sprays. For a 160g/li product such as Beetup this is equivalent to 6.0li/ha. Unfortunately some labels are now written so that the number of applications is also limited. In the case of Beetup the limit is 3. To date these limits applies only to the product you are using, so switching to different product is still permissible. On fen soils with protracted weed emergence it would not be uncommon to require more than 6.0li/ha in more than 3 applications during a season.
Ethofumesate has a restriction that limits the total dose to 1000g/ha in any 3 year period. Potentially a problem where crops such as grass for seed are grown in the same rotation.
SMR 9 compliance: I thought it worth reminding you of these requirements. The inspectors are being asked to check the following points when inspecting pesticide usage.
1. Products are approved
2. Products are approved for intended use
3. Products approved for intended method of application
4. Maximum dose/concentration not exceeded
5. Maximum number of treatments/total dose not exceeded
6. Application dates/ harvest intervals observed
7. Access restrictions for workers/livestock observed
8. Notification given e.g. When spraying sulphuric acid.
9. Adherence to principles of good plant protection practice as set out in code of practice
• LERAPs carried out if required
• Application carried out by holders of certificates of competence
• Appropriate measures for preventing and controlling spillages
• Sufficient PPE
• Emergency action plan prepared
In recent years most failures have been the result of lack of operator certification.