PGRO’s top tips for a successful spring bean crop
15 Feb 2021
By Jane Kitchen, BASF Capaign Manager
On our most recent Real Results Virtual Farm webinar, PGRO’s R&D Manager Becky Howard joined me to discuss how to get the most from spring beans.
1. Soil Structure
“One of the key factors which can affect how field beans form is soil structure. So, it is really important to get conditions right before you start.”
“Compaction tends to reduce root development and can reduce yield by up to 40%. When soil moisture deficit is high, poor soil structure compounds the issue causing severe moisture stress,” she said.
Dr Howard continued to explain that although faba beans are the most tolerant of grain legumes to waterlogging, long-term submergence can cause irreversible damage to roots.
2. Seed Quality
It is extremely important that growers ensure seed is tested for germination, pests and diseases, explained Dr Howard.
“Germination capacity should be 80% or more,” she said. “It is also important that seed is free of stem nematode (a seed and soil-borne pest) and should have no more than 1% Ascochyta Fabae - while there is a foliar treatment available there’s no seed treatment to control this in beans.”
3. Cultivation and Establishment
“Beans don’t require a fine seed-bed, but a level seed-bed will improve herbicide efficiency. It is also very important to wait for the correct conditions, don’t force spring beans into the ground,” warned Dr Howard.
Minimal tillage and direct drilling are becoming more commonly used, where this approach is being deployed Dr Howard said:
“The seed should be well covered, with no open slots and good seed-to-soil contact. To achieve optimum establishment, drilling depth should be 10-12.5cm.”
She also emphasised that legumes should not be grown more than one in five years, largely for disease management and control.
4. Sowing and Seed Rate
Optimal sowing time for sowing spring beans is mid-February to late March and seed rate should aim to establish 50-55 plants per metre squared, with 40 plants per metre squared on very fertile land. Allow 5% field loss when calculating seed rate for plant rates.
Dr Howard recommends using the Optibean tool on the PGRO website, or the PGRO App, to help calculate the correct seed rate.
5. Disease Control
Chocolate spot and rust are the two diseases most likely to be present in spring beans. Downy mildew is moderately common and all three can impact yield significantly.
Chocolate spot can cause up to 50% yield loss, rust can cause up to 70% loss and downy mildew up to 30% loss.
“Chocolate spot, is a cool, wet weather disease, and downy mildew is encouraged by cool, humid, overcast conditions” explained Dr Howard.
“Bean rust, on the other hand, is a warm weather disease, which develops quickly and is favoured by hot days and cool humid nights. Products can be applied with the second chocolate spot spray.”
“It is likely that a two-spray programme for spring beans will be required but possibly only one, if conditions are favourable.”
“At T1, first pod, chocolate spot is the target. And the options are: Signum® OR azoxystrobin + tebuconazole / metconazole OR cyprodinil + fludioxonil. If downy mildew is present on 25% of plants or more, growers can include SL 567A (metalaxyl-M).”
“3-4 weeks later, at T2, chocolate spot and rust are the targets. Here, the options are Signum® OR azoxystrobin + tebuconazole / metconazole.
Tebuconazole may only be applied to the crop once."
Dr Howard advises to look at the Pulse Descriptive List for descriptions on tolerant varieties.
Pea and Bean Weevil
Dr Howard recommends growers to place pheromone monitoring traps in field margins of previous years legumes by mid-February. If growers haven’t grown legumes before, she advised growers to place traps in the margins of the current crop.
“Check traps three times each week and consider control options in current crops if the threshold of 30 weevils per trap is reached, and the crop is newly emerged or will emerge in the following 10 days. When the threshold is reached, spray when first notches are seen on plants.”
Both pea and bean aphids can damage yield significantly but there are a number of biological controls which can help reduce or spread numbers.
“Two-spotted ladybirds, predatory wasps, organic surfactants and plant extracts are available to consider as methods of biological control.
“Research in Europe has shown that intercropping may be useful in providing barriers, diluting the effects of the pests and by changing the crop’s micro climate,” added Dr Howard.
Insecticides are also available to control aphids in spring beans.
This type of pest causes damage to the harvested seed and is a later flying pest. It moves into crops from April onwards, particularly into flowering crops where females feed to become reproductive.
“Spray bruchid beetle when the maximum daily temperature has reached at least 20 degrees for two consecutive days and when crops are at the first pod stage,” said Dr Howard.
She emphasised the need to check pyrethroid labels for flowering restrictions.