Time to Zero-In on Zero Residues


Louise Labuschagne reports:

When politicians need to negotiate safe passage through a minefield of difficult issues – they make a Road Map. Real IPM Kenya is putting its money where its mouth is and making its Road Map to Zero Residues a very public affair. Progress reports are published on social media (#zeroresidues) and include step-by- step progress reports and YouTube videos. The greenhouse, in Thika (Kenya) is open to rose growers to see for themselves and even take samples to test for chemical residues. The programme started two weeks ago and is already showing very encouraging results. By the time the Nairobi IFTEX Show is running there may be even more to shout about.
They are attempting to demonstrate that even in a very highly infested rose crop, with a highly susceptible variety, on the Equator with all year round growing conditions and during the rainy season – that it is possible to use biological controls curatively for all pests and diseases in roses. If it is possible to get out of the quagmire just using biological controls – they hope to encourage growers to be more confident about using a bio-intensive IPM programme as the front line way for all growers protect their crops in the New Age of Rose Farming. A prophylactic, preventive programme with high application rates and short spray intervals for biopesticides and predatory mites is claimed to be the most sustainable and reliable way to improve yield and quality – is this true? Their challenge to rose growers everywhere is SEE IT – BELIEVE IT – DO IT

When retailers task their suppliers to reduce chemical pesticide residues, growers hear alarm bells ringing. The immediately envisage huge crop losses, irate buyers on the phone and foresee a fast scramble back to the safe bunker of programmes that rely on chemical pesticides.

Measuring risk and progress

It is not unusual for growers trying bio-intensive IPM to jump ship when they are not sure about achievements or risks. The #zeroresidues rose greenhouse is being scouted using the Scarab Solutions state of the art GPS scouting system. Hand-held smart phones are used by trained scouts to enter information on the presence and severity of the pests and diseases at about 13 observation pints in a 40-meter row. This data is even separated into three strata inthe crop (base, middle and top).

Within three minutes of pressing ‘send’ to have the data analysed by Scarab Solutions – a very detailed contour greenhouse map of the individual pests are displayed either on the phone or on a number of computers anywhere in the world.

Managers with passwords can immediately see the progress of powdery mildew control or mealybug control etc. – even if they have not been able to visit the greenhouse. Not all farm managers would want the owners breathing down their necks from another country. But eventually with a successful bio-intensive programme, the farm manager will have less to worry about. Ethan Chege, Technical Manager at NIRP Show-house in Kenya says “ I sleep at night now – knowing that I am in control, having successfully implemented the bio-intensive spray programmes”.
Scarab is a very useful tool because it is impossible to ‘cheat’ with the scouting – since the week-on- week comparison of hot spots and spread of disease or pests takes a biologically logical route. Access to this technology and the immediate reports – replace piles and piles of un-read scouting data from the old fashion scouting methods! The Real IPM #zeroresidues rose greenhouse will be publishing key comparisons of ‘before’ and ‘after’ the bio-intensive spray programme.

Powdery mildew history
Rose growers around the world have serious problems with powdery mildew and may have to spray up to 50 times per year for this disease. If growers could replace fungicides with biological controls – they could make a serious dent in their performance targets for #zeroresidues. Already after only two weeks, the Real IPM programme has made powdery mildew ‘history’. Powdery mildew on the stems and leaves were at seriously high levels. The Scarab powdery mildew maps show how this turnaround has happened.

Fig 1 : Scarab map BEFORE the Real Bacillus subtilis programme started. Circles indicate where live powdery mildew was observed on the stems near flower heads.


Fig 2: Scarab map AFTER 40 days of the Real Bacillus subtilis programme. This has been achieved without any chemical fungicides.

Therefore a prophylactic preventative programme is a reliable substitution for fungicides and runs no risk of resistance developing.

Over the next few weeks, similar results are expected on downy mildew, mealybugs and thrips. These are all difficult targets, even for chemical fungicides and insecticides. But even after two weeks – the Scarab maps are showing significant improvements using higher rates of biopesticides and shorter spray intervals for curative programmes.

Lower spray volumes of water are key to the success of biopesticides. They must not be sprayed to ‘run-off’. Successful bio-intensive growers have had excellent results with just 800 litres of water volumes per hectare for pest and disease control.