Planting has got underway in generally good conditions although until now, soil temperatures have been pretty low, struggling to get above 5-6C. I have received a number of phone calls from growers asking for my opinion on soil temperature. My answer is based on a number of factors including variety, how much they have to plant and soil conditions. If they have a lot to plant and the soil conditions are right, crack on. One thing that I have noticed is that soils cultivated after a green manure crop have worked extremely well, contributing to the overall condition of the soil.
For those growers who have their seed already in cold store awaiting planting, here are a few pointers:
- Always aim to plant seed that is colder than the soil temperature (if a minimum soil temperature of 7C is the guideline, then seed should be below this)
- Removing seed from a cold store almost always results in condensation forming where the outside air is even a few degrees above this. If it will be some time before the seed is planted, keep in a draughty place such as a Dutch Barn to ensure the condensation evaporates
- Assuming around two days are required to remove condensation, remove seed around two days before planting is planned. The tuber temperature will not rise substantially in two days. Removing condensation is important if seed tuber dust treatments are to be applied
- If it looks as if weather will delay planting for a few days, place seed back in the cold store once condensation has gone.
Soon thoughts will be on weed control and herbicide choice. Weed control is always much easier when emergence and growth is quick as the canopy often out competes emerging weeds and smothers them out. A cool spring is often more challenging, with much more reliance on residual activity.
If possible apply your residual when there is moisture in the ridge. It is worth remembering that actives such as prosulfocarb and pendamethalin are not that soluble, so they work much better when moisture is available. In my opinion metribuzin remains the key active ingredient to ensure successful weed control, particularly if conditions are dry. Metribuzin can now be purchased in both liquid – suspension concentrate (SC) – form (Sencorex Flow) and in water dispersible granule (WDG) form (various products). Both formulations will have the same variety restrictions for pre- and post-emergence use and there is slightly less active in the liquid formulation.
There are two new products that might be worth a look, although I have little experience with them. The first is pyraflufen–ethyl known as Quickdown from Certis, it is an alternative contact to diquat (e.g. Reglone) or carfentrazone (Shark) and is claimed to have better control of cleavers and bindweed, although there is no activity on annual meadowgrass (AMG). The second is metobromuron, known as Praxim from Belchim, and comes from the same herbicide group as linuron. It is active on chickweed, charlock, fat hen, pansy, groundsel, knotgrass, mayweed and shepherds purse though not on cleavers or AMG and can be used on all soil types. It is likely to be a useful partner product with metribuzin, although cost is likely to dictate the application rate.