New-generation fruitlet thinner: over 800 trials, 27 nations. And counting.
Launched in New Zealand in 2017 by ADAMA NZ, photosynthesis-inhibiting fruitlet thinner Brevis promised a step-up from costly hand thinning and hit-and-miss plant hormone-based thinners in apples and pears.
Brevis is now backed by over 800 apple and pear trials to date in both the Northern and Southern Hemispheres. A commitment to sharing that information saw ADAMA’S Global Brevis Project Manager Ton Besseling travel to New Zealand from the Netherlands in July to meet with local advisors and growers.
Ton says research has been critical in finding the best timing for Brevis application and as a result, getting optimum thinning results.
ADAMA has amassed in-depth knowledge of the impact of weather and other factors on Brevis’s thinning efficacy. Variables considered include the effects of night time temperatures, radiation (sunlight), humidity, and different apple and pear varieties (easy, medium and hard to thin).
Continuous trial work vital
Importantly, the trials do not stop with registration.
Ton says continuous trial work is vital to maintain support for advisor and grower decision-making, especially since thinning is such a critical and stressful time for growers.
He explains that the availability of carbohydrates is the key to the effectiveness of fruitlet thinning with Brevis. Brevis mimics the effect of shading, reducing the production of carbohydrates by the tree. Remaining carbohydrates are sent to shoots and to the largest, dominant “king” fruitlets at the expense of smaller fruitlets, which stop growing and start to drop from the tree in 7 to 10 days.
Radiation and night time temperature most important factors
The trials on weather and temperature show the efficacy can be amplified or lessened requiring dose adjustments.
“For example; if you have cloudy weather after you apply Brevis, expect a stronger result, because there are less carbohydrates available to the fruit, combined with the effect of Brevis.
“We also found, some years ago, that night time temperatures are one of the most important factors in the efficacy of Brevis. It has to do with the degradation of carbohydrates so, if you have high night time temperatures you get strong degradation of carbohydrates and less are available to the fruit, so the thinning effect is promoted. On the other hand, if you have low night time temperatures you will have more carbohydrates in the tree.”
Giving advisors and growers greater control
Because of its unique mode of action, Brevis is significantly less temperature dependent than plant hormone-based thinners. Applied when fruitlets are between 8 and 14 mm, Brevis can be sprayed at temperatures between 10 and 25ºC, reducing uncertainty and guesswork. This is in contrast with other thinners, which have very specific temperature requirements at and following the time of application.
Ton says putting greater control and autonomy in the hands of advisors and growers is driving the science behind Brevis.
Using fruitlet thinners only
Being a secondary fruitlet thinner, Ton says Brevis will “do the job on its own without the need for primaries” an approach, ADAMA NZ says, local growers are increasingly adopting. Ton is quick to add that “If a grower still wants to use a primary thinner as well, that’s not a problem and it doesn’t affect the efficacy of Brevis.”
The Brevis label covers both single and split applications. The latter, Ton says, allows for even more precise fine-tuning for weather conditions or if the grower wants to stress the tree longer.
No need for surfactants
Other benefits include that Brevis does not require the addition of surfactants, making it easy to use. It is also rain-fast within two to three hours. As Brevis is non-toxic to beneficial organisms, it is an excellent fit for IPM programmes. Moreover, orchard re-entry is possible after just three days, minimising disruptions to orchard routines.
ADAMA currently has Brevis registered in 27 countries and expects to extend that to 31 within the next four years. This will give the fruitlet thinner a presence in 90% of the world’s apple and pear producing nations.