Crop production: Beating bollworm with biological products


By Johan Van der Merwe | 13 February 2018
bollworm
Photo: Supplied

Biological products proved to be the best weapon against bollworm for paprika farmers in South Africa’s North West Province following a great deal of damage and enormous expenditure on chemical control products.

“We bred super worms,” explains Stephan Niemann, a paprika farmer from the Stella area in South Africa (SA). “We were so desperate we mixed chlorpirifos and pyrethroid, but that didn’t help at all. Season after season we lost up to 20% of our paprika harvest to worms,” Niemann explains.

According to Pieter de Villiers, who also produces paprika near Stella, the rising costs of chemical products and yield losses due to the worms had a significant effect on the profitability of his farm.

THE PRICE OF POISON

Niemann sprayed chemicals 3 times every 24 days to interrupt the bollworm’s life cycle. “I was on a cycle of 7 days, 7 days and 10 days between each application. My bill for chemical products in 2014 was higher than R1.5 million,” he says.

De Villiers contacted Jaco Meyer at Metanoia Agri in 2014. “We spoke by phone after I dialed the wrong number and I described the bollworm problem we were experiencing to him. He suggested Wormguard and the rest is history,” he says.

Niemann and De Villiers both still make use of their normal chemical pesticide programme, except for combatting bollworm. For this they use 1l/ha Wormguard, which is applied twice each season by either tractor or from irrigation pivot points.

The first application of 500ml/ha occurs at 8 weeks after emergence, just before fruitset, with the second application, also 500ml/ha, 6 weeks later when bollworm pressure is traditionally experienced.

“We’re applied the Workmguard with a tractor at low pressure and low volume (250ml/ha), followed by a 3 mm irrigation as it is a systemic product. The bollworm loves to eat the stem collar of paprika’s seed pod. The pod then drops off or rots on the plant. With the biological products, the worms simply don’t eat the paprika,” Niemann explains.

DOUBLED YIELD

Photo: Supplied

Initially Niemann did trials with biological products on 4 different irrigation pivot points, where 2 were treated with chemical products and 2 with biological products. The average yield on the chemically treated fields was 2.8 ton/ha, while the fields treated with biological products produced more than 6 ton/ha.

“Moreover, my bill for chemicals has been cut to less than R500 000 per year,” says Niemann. Both farmers have learned some valuable lessons with biological products. “The products are often sensitive to high pressure. I’ve tried applying biological products through a pivot point with high pressure, but you may as well not apply anything if it’s done this way. So, you have to be careful and ensure that the pressure of the pivot or tractor sprayer isn’t higher than 3 Bar.

UNDERSTAND THE BIOLOGY

“It helps to understand the biology behind the products. Don’t just read the advertisements and see dollar signs flashing. If you understand how the products work and which organisms work in which ways, you can go about developing an effective, integrated programme for your farm.

“This is why it’s so important to build a good relationship with a trustworthy supplier that knows what he or she is talking about. We’ve come across chancers before and paid dearly for that lesson because you don’t only use ineffective products, you also endanger your harvest,” De Villiers says.

Niemann adds that timing is important and that you can’t just mix different products together, or apply them in too close succession. “Many of the biological products destroy each other, so you can’t keep them in the same tank or apply them too soon after each other. We also only spray Wormguard at night because it’s sensitive to UV radiation.

“Chemical fungicides we use also destroy Wormguard because it’s a bacterium. During our first application we sprayed a copper application on the paprika as a fungicide, but didn’t account for it that the copper also kills the bacteria. Now, before we apply Wormguard, we apply no fungicide for at least 7 days.

“If we detect a problem with fungi just before fruitset, we apply a contact fungicide by the last week 7 and then give it 10 days before we apply Wormguard. You can apply a fungicide again a week after this again, because then the Wormguard will already be absorbed and you won’t destroy the efficacy of the product. So, there are adjustments to be made, but it pays well,” says Niemann.

According to Jaco Meyer, owner of Metanoia Agri, and Dr. Johan Kruger, founder of BacTech, Wormguard is the same bacterium that is used in the Bt-gene to protect maize against borers.

Contact: Jaco Meyer at jaco@metanoia-agri.co.za or on +27 82 879 0220.

Also read: Vegetable production: Heat up your cash flow with chillies