Potato Review

12 POTATO REVIEW JULY/AUGUST 2020 DESICCATION AND FLAILING “AHDB ailing costs are put at £127/ha (£51/acre). is assumes there is a 200hp + tractor + operator surplus to requirements at the busiest time of the year when potato harvesting is under full swing. “Traditionally a two or three-row trailed harvester has been used by a typical grower (pre diquat ban) with a front linkage, PTO and front- mounted side delivery topper which is not ideal for ailing three weeks before harvesting owing to the side delivery system putting all the haulm in one point as opposed to spreading it equally down all the wheelings. In many cases, this could mean tractor upgrades when going to six-row ailing, which could mean extra costs to the business over and above the table above.” Another factor to consider is the bene t of ailing when green. David said you get a better cut and mulch when haulm is green, while very little dust is created compared to harvesting with front mounted topper in the dry, which can cause visibility issues and blocked radiators and overheating engines, which can be costly. If you do not leave too much stem (he suggests 4” to 6”) then re topping at harvest should not be necessary, he said. “Our Scott ail has rubber press wheels on the back which, when dry, is a real bonus and helps to prevent soil cracking which can lead to more green potatoes. If soil is wet however, they can be lifted up out of the way. Some growers can get nervous about possible compaction if wet conditions prevail. Even in the wet autumn of 2019, this did not prove a problem. We researched the narrow crop wheels and tyre options and decided to invest £6,000 in extra tall wheels which t well in our JD 6250R with variable ex tyres which can be operated at 30psi. All this adds up to a larger footprint for 380 width tyres.” Contracting charges for an average crop with a 400-acre block of work to do over a period will be signi cantly less than the AHDB £51/acre and in many cases will hover around the £40/acre mark. Mark Taplin of Harvest Agronomy Limited said as long as the crop and weather conditions are suitable, then e ective ailing prior to a PPO chemical desiccant will facilitate prompt haulm desiccation and skin set for storage crops. “ e quality of the ailing operationprior to chemical desiccation is critical and care should be taken to ensure this is carried out properly,” he said. E ective haulmmanagement improves storage e ail and spray method of haulm destruction and crop desiccation has long been a feature of potato farming operations at Bannister Farms Ltd, near Boston in Lincolnshire. By managing crop canopy size, using modern topping machinery and a tried and tested desiccant on the farm each season, haulm growth can be stopped quickly and crops made ready to enter long-term storage in the best possible condition according to farmmanager TomMacfarlane, who oversees the arable enterprise that includes 130ha of maincrop potatoes alongside cereals, vining peas and sugar beet, all grown on light alluvial silt. Up to 50% of the farm’s potato varieties are Maris Piper and Desiree – both known for their large canopies. When diquat was still available, Tom said an application of the herbicide was sometimes made ahead of the ail and spray operation to reduce leaf matter further. Since its withdrawal, Tom has been experimenting with nitrogen rates and trialling reductions to better tailor what the crop requires. “We aim for crops to start naturally senescing as best they can to help with the ail and spray operation, but there is a balance between achieving this and pushing for maximum yield,” he said. All nitrogen applied goes in the seedbed at planting and with an increased understanding of residual nitrogen remaining in the soil following other crops in the rotation, Tom has reduced overall N input by about 20%. “By doing this we are saving money on inputs and setting the crop up nicely for ail and spray by reducing canopy size,” he said. Topping is carried out on the farm by a new, six-row Dutch-made Struik machine, with the aim of leaving 5–6in stems exposed for the following spray. “We usually wait two to three days after the ail before applying the desiccant and this gives time for any remaining trash to wilt, leaving the stems clear. at said, modern toppers are very good at placing the bulk of the green haulm in the bottom of the furrow,” Tom said. Stem desiccant Spotlight Plus (carfentrazone) at 1l/ha is applied using a water volume of 300l/ ha. “It’s really important to be patient at this point and let the chemical do its work,” said Tom. “Crops are monitored for any regrowth, which can be a ected by the weather conditions at the time or the level of nitrogen in the crop. A follow- up spray of 0.6l/ha Spotlight Plus can be applied if there are any regrowth issues.” Spotlight Plus comes with no bu er zone requirement and has the additional bene t of only a seven-day harvest interval, although this “The quality of the flailing operation prior to chemical desiccation is critical.” Farm manager Tom Macfarlane advocates the flail and spray method of haulm destruction and crop desiccation. Agronomist Andrew Sprunt stresses the importance of using the correct flail and set up.