Barclay Crop Protection

Boron - Vital for Oilseed Rape Potential

Growers of oilseed rape, some of whom are returning to the fold this year, are been reminded of the crop's appetite for a crucial trace elements. In recent years we have seen a much higher percentage of growers waking up to the potential of hybrids but we need to be constantly aware that higher potential generally means higher nutritional requirements.

Many of us would routinely lime ahead of a Rape crop and this alone can lead to reduced availability of nutrients in the soil such as Manganese, and Boron, both of which are needed by growing  plants and even more so with these modern hybrids which exhibit such high levels of autumn vigour.

Boron especially is vital in rape's metabolism, with highest demand occurring when the crop is actively growing. These young plants need to rapidly develop their root systems to supply vital anchorage as well as moisture and nutrients during it's life. At this time any shortage of nutrients can have a critical impact upon both survival and potential. With boron being so heavily involved in cell wall structure, the plant places a huge demand on the element during root and shoot establishment.

"All  growers are determined to ensure the new crop  gets off to a good start and this year most OSR crops are hugely ahead because of the continuing warm conditions," says Paul Haynes  of Barclay Crop Protection. "Because so many crops are very forward and also denser than expected, the demand upon soil reserves is going to be higher. Whilst many growers would happily sacrifice some plants it is probably more vital that we focus on nutritional availability and especially that boron levels are maintained as denser crops have a higher lodging risk so we need the strongest root systems possible."

"Where rape is already in the rotation then these soils are the most likely candidates for treatment," adds Mr Haynes, "current cropping trends mean that many of these crops will be on closer than ideal intervals and as at least 80grams/ha of boron is removed at harvest, growers need to be maintaining the levels of the minor and micro nutrients as well as the major ones".

"With an estimated crop requirement of 1 to 1.5Kg/ha of Bo, split applications of an autumn  application of boron such as Solubor ensuring the best conditions for good root establishment, then follow up with the balance at the usual  pre-flowering application in spring".  He points out "This way growers can ensure stronger, healthier root systems throughout the crop providing a healthy, vigorous transport system to guarantee good nutrient supply through the plant meaning it will benefit more from the follow up application in the spring".

An autumn application will be best timed to fit in with existing herbicide and fungicide treatments.

"Because it's a foliar application, it's very simple to incorporate Solubor DF into a tank-mix such as an application of propyzamide or autumn fungicide without increasing the work load or creating extra passes with the sprayer".

"Soil testing pre-planting should have revealed any underlying  deficiency giving growers plenty of time to make any decisions," advises Mr Haynes, "however at this stage, leaf tissue analysis will give a more accurate picture of what is going on in the plant and provide target requirements for any  necessary boron applications.  It may even be the case that visual symptoms are already present if the deficiency is severe," he adds, "these may be showing  with new leaves being deformed, they may have cracked petioles and be bent back; stem elongation will be restricted and  the plants will be stunted. In extreme cases the growing point may die. Branching may be excessive and hollow cracked plant base and root."

Where a shortage is identified, Mr Haynes urges growers to adopt a split programme. "The recommended rate for Solubor is 2-3kg/ha, but I'd suggest two applications if there's the opportunity in your planned spray programme," he says. "the advanced crops need the help and leaf area should provide good interception and uptake, so suggest  split the overall dose applying  1.5kg now followed by the remaining 1.5kg pre-flowering . This should ensure the plant is able to make best use of the element."