Hugh Gillan farms 135ha at Drumcarro Farm overlooking the picturesque landscape of St Andrews in east Scotland. He grows a combination of organic wheat and oats as well as lambing a pedigree Lleyn flock. Leatherjackets continue to be the number one pest on his farm, but through using cultural techniques he has perfected their control.
Organic farming
After turning down the opportunity to move to Australia and start a farming enterprise 14 years ago, Hugh made the decision to convert to organic farming in the search of a higher profit margin.
Hugh grows 30ha of organic, high hagberg winter wheat which is sold to be processed into fish food. He also grows another 30ha of spring oats for the porridge market. The remainder of the farm is sown in a grass/clover mix and is grazed by his 310 pedigree Lleyn flock.
Hugh operates a four-year rotation. Year one consists of winter wheat. He grows the variety Revelation due to its high disease-resistant rating.
“Most farmers look at varieties on the recommended list and tend to look to the highest-yielding ones and don’t prioritise the disease-resistant aspect. There are a few varieties out there that aren’t the highest yielding but have good disease resistance – these are the ones we choose because we don’t have a choice.”
The second year consists of spring oats for the porridge market which is under-sown with a grass/white clover mix. He generally sows his oats at rates of 160kg/ha with a one-pass drill. He then broadcasts 13kg/ha of grass seed and white clover and incorporates them using his PICO harrow. As the crop is under-sown with grass and clover, once the oats are harvested, the field can be grazed immediately.
The grass clover mix is grazed by his pedigree Lleyn flock for two years before being ploughed and sown with winter wheat.
Hugh applies some organic sheep manure to his crops – approximately 12t/ha of sheep manure as well as a couple of tonnes of pen when available. However, the real source of nitrogen (N) comes from the under-sown white clover, explains Hugh. It fixes nitrogen over the three years in the ground and makes it available to the following wheat and oat crops.
“If you don’t have clover in the mix, you can forget about organic, I get some organic N from manure but the real secret is from using clover.”
As a result, Hugh can achieve organic winter wheat yields of between 5.4t-6.4t/ha and up to 3t/ha of organic spring oats.
However, a two-year break of grass clover followed by winter wheat presents a significant pest problem, namely leatherjackets.
Leatherjacket problem
Leatherjackets can be an agricultural pest because they eat and damage emerging crops in the grass family in spring. Grass and cereals are particularly at risk from leatherjacket damage. Severe leatherjacket infestations can lead to significant crop damage.
The leatherjacket life cycle
Hugh stressed the importance of understanding the life cycle of the leatherjacket in order to develop an effective control technique. Leatherjackets are a large grey grub which are the larva of a large type of crane fly (Tipulidae spp.) commonly known as the Daddy Longlegs. They mostly live within the soil and have thick grey-brown leathery skin, no legs and can grow up to 5cm in length.
There are a number of key stages to the leatherjacket’s life cycle: emergence of adults from pupae; flight; egg laying; larvae hatch; growth and then pupating (turning into adults). The Tipulids species spends most of its time as leatherjackets and hardly any time as adults. They are at their most damaging when they are reaching maturity.
The adult crane flies emerge from grasses in late summer/autumn. They generally mate within 72 hours and lay their eggs soon after. Adult flies are large, with clear wings, a long body and long delicate legs, and resemble giant mosquitoes.
They tend to lay their eggs on grasses to ensure a supply of food for the larvae. The leatherjacket larvae hatch a few weeks later and begin to feed immediately, mostly on roots and underground stems during the day and plants above the ground at night.
The larvae over-winter and continues to grow until they reach maturity in mid-to late spring just below the soil surface. In late summer and autumn, adult crane flies emerge to start the cycle again.
Control method
In conventional non-organic farming systems, the insecticide Dursban was the chief method of control for leatherjackets. Dursban contains an organophosphate chemical that is effective at killing leatherjackets at all stages of their lifecycle, no matter how big they are. However, in March 2016 the chemical was banned from use. This left no chemical control method on the market.
This is where Hugh’s method of control is of particular interest. Given his organic status, chemical control hasn’t been an option for many years. With his grass clover-cereal rotation, the risk from the pest is heightened.
He first stumbled across this cultural method of control in 2012 during a particularly bad year for leatherjacket damage. Before drilling 28ha of winter wheat, he gave one part of the field an extra pass with his cultivator after ploughing in August because he didn’t think it was suitably cultivated for drilling. Around three weeks later he gave the same area anther pass with the cultivator.
After drilling and rolling the 28ha of winter wheat, leatherjackets virtually wiped out most of the field. However, the areas of the field which received the double cultivation were untouched by the pest.
Disrupting the lifecycle
Hugh’s method of control centres on disrupting the lifecycle of the leatherjacket and he has since refined it to a tee. As the crane fly prefers to land on grass – particularly old grass – to lay its eggs and ensure food for the larvae, Hugh tightly grazes and even tops his grass clover fields before ploughing them by 10 August.
“It would make me very nervous now not to be sowing a field into September. I had one field last year where we couldn’t plough until 18 September and it was badly hit with leatherjackets.”
Hugh maintains the crane fly will be less likely to land and lay its eggs on ploughed ground. Soon after ploughing, when the ground is dry enough, he uses his Bomford Dyna-Drive ground-driven cultivator to till the field. This will kill any crane fly eggs that are present but will also help germinate weeds, Hugh explains. Two to three weeks later he returns to the field and cultivates again in a different direction. This again will kill any eggs which are present as well as kill any germinated seeds.
Soon after, he drills the field with his one pass drill. “I set myself a deadline to have everything drilled by 5 October. I’ll go day and night if I need to. I want to see the plants come up through the ground by middle of October”.
He then double-rolls the field after drilling.
Through early ploughing, crane flies are discouraged from landing in his fields to lay eggs during that stage of their lifecycle. Through double cultivations, any eggs which are laid are destroyed. The one-pass creates a fine seed bed and double rolling increases its firmness, which is a key deterrent for leatherjackets by reducing their ability to move through the ground. These cultural methods of control give five-star control, according to Hugh.
Key points
Hugh’s organic farm runs a four-year rotation consisting of winter wheat, spring oats and two years of grass clover.Clover is the key to achieving high yields in organic systems.Winter wheat following grass clover is the perfect recipe for leatherjacket infestations.Hugh’s method of control consists of disrupting the pest’s lifecycle through early ploughing, double cultivations and double rolling.
Hugh Gillan farms 135ha at Drumcarro Farm overlooking the picturesque landscape of St Andrews in east Scotland. He grows a combination of organic wheat and oats as well as lambing a pedigree Lleyn flock. Leatherjackets continue to be the number one pest on his farm, but through using cultural techniques he has perfected their control.
Organic farming
After turning down the opportunity to move to Australia and start a farming enterprise 14 years ago, Hugh made the decision to convert to organic farming in the search of a higher profit margin.
Hugh grows 30ha of organic, high hagberg winter wheat which is sold to be processed into fish food. He also grows another 30ha of spring oats for the porridge market. The remainder of the farm is sown in a grass/clover mix and is grazed by his 310 pedigree Lleyn flock.
Hugh operates a four-year rotation. Year one consists of winter wheat. He grows the variety Revelation due to its high disease-resistant rating.
“Most farmers look at varieties on the recommended list and tend to look to the highest-yielding ones and don’t prioritise the disease-resistant aspect. There are a few varieties out there that aren’t the highest yielding but have good disease resistance – these are the ones we choose because we don’t have a choice.”
The second year consists of spring oats for the porridge market which is under-sown with a grass/white clover mix. He generally sows his oats at rates of 160kg/ha with a one-pass drill. He then broadcasts 13kg/ha of grass seed and white clover and incorporates them using his PICO harrow. As the crop is under-sown with grass and clover, once the oats are harvested, the field can be grazed immediately.
The grass clover mix is grazed by his pedigree Lleyn flock for two years before being ploughed and sown with winter wheat.
Hugh applies some organic sheep manure to his crops – approximately 12t/ha of sheep manure as well as a couple of tonnes of pen when available. However, the real source of nitrogen (N) comes from the under-sown white clover, explains Hugh. It fixes nitrogen over the three years in the ground and makes it available to the following wheat and oat crops.
“If you don’t have clover in the mix, you can forget about organic, I get some organic N from manure but the real secret is from using clover.”
As a result, Hugh can achieve organic winter wheat yields of between 5.4t-6.4t/ha and up to 3t/ha of organic spring oats.
However, a two-year break of grass clover followed by winter wheat presents a significant pest problem, namely leatherjackets.
Leatherjacket problem
Leatherjackets can be an agricultural pest because they eat and damage emerging crops in the grass family in spring. Grass and cereals are particularly at risk from leatherjacket damage. Severe leatherjacket infestations can lead to significant crop damage.
The leatherjacket life cycle
Hugh stressed the importance of understanding the life cycle of the leatherjacket in order to develop an effective control technique. Leatherjackets are a large grey grub which are the larva of a large type of crane fly (Tipulidae spp.) commonly known as the Daddy Longlegs. They mostly live within the soil and have thick grey-brown leathery skin, no legs and can grow up to 5cm in length.
There are a number of key stages to the leatherjacket’s life cycle: emergence of adults from pupae; flight; egg laying; larvae hatch; growth and then pupating (turning into adults). The Tipulids species spends most of its time as leatherjackets and hardly any time as adults. They are at their most damaging when they are reaching maturity.
The adult crane flies emerge from grasses in late summer/autumn. They generally mate within 72 hours and lay their eggs soon after. Adult flies are large, with clear wings, a long body and long delicate legs, and resemble giant mosquitoes.
They tend to lay their eggs on grasses to ensure a supply of food for the larvae. The leatherjacket larvae hatch a few weeks later and begin to feed immediately, mostly on roots and underground stems during the day and plants above the ground at night.
The larvae over-winter and continues to grow until they reach maturity in mid-to late spring just below the soil surface. In late summer and autumn, adult crane flies emerge to start the cycle again.
Control method
In conventional non-organic farming systems, the insecticide Dursban was the chief method of control for leatherjackets. Dursban contains an organophosphate chemical that is effective at killing leatherjackets at all stages of their lifecycle, no matter how big they are. However, in March 2016 the chemical was banned from use. This left no chemical control method on the market.
This is where Hugh’s method of control is of particular interest. Given his organic status, chemical control hasn’t been an option for many years. With his grass clover-cereal rotation, the risk from the pest is heightened.
He first stumbled across this cultural method of control in 2012 during a particularly bad year for leatherjacket damage. Before drilling 28ha of winter wheat, he gave one part of the field an extra pass with his cultivator after ploughing in August because he didn’t think it was suitably cultivated for drilling. Around three weeks later he gave the same area anther pass with the cultivator.
After drilling and rolling the 28ha of winter wheat, leatherjackets virtually wiped out most of the field. However, the areas of the field which received the double cultivation were untouched by the pest.
Disrupting the lifecycle
Hugh’s method of control centres on disrupting the lifecycle of the leatherjacket and he has since refined it to a tee. As the crane fly prefers to land on grass – particularly old grass – to lay its eggs and ensure food for the larvae, Hugh tightly grazes and even tops his grass clover fields before ploughing them by 10 August.
“It would make me very nervous now not to be sowing a field into September. I had one field last year where we couldn’t plough until 18 September and it was badly hit with leatherjackets.”
Hugh maintains the crane fly will be less likely to land and lay its eggs on ploughed ground. Soon after ploughing, when the ground is dry enough, he uses his Bomford Dyna-Drive ground-driven cultivator to till the field. This will kill any crane fly eggs that are present but will also help germinate weeds, Hugh explains. Two to three weeks later he returns to the field and cultivates again in a different direction. This again will kill any eggs which are present as well as kill any germinated seeds.
Soon after, he drills the field with his one pass drill. “I set myself a deadline to have everything drilled by 5 October. I’ll go day and night if I need to. I want to see the plants come up through the ground by middle of October”.
He then double-rolls the field after drilling.
Through early ploughing, crane flies are discouraged from landing in his fields to lay eggs during that stage of their lifecycle. Through double cultivations, any eggs which are laid are destroyed. The one-pass creates a fine seed bed and double rolling increases its firmness, which is a key deterrent for leatherjackets by reducing their ability to move through the ground. These cultural methods of control give five-star control, according to Hugh.
Key points
Hugh’s organic farm runs a four-year rotation consisting of winter wheat, spring oats and two years of grass clover.Clover is the key to achieving high yields in organic systems.Winter wheat following grass clover is the perfect recipe for leatherjacket infestations.Hugh’s method of control consists of disrupting the pest’s lifecycle through early ploughing, double cultivations and double rolling. 
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