7/10/19 - 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.”