MaxCel® Provides Supreme Benefits on Tree Fruit

apple fruitlets on a tree

Ideal for application on apples and pears.

MaxCel is formulated with a built-in surfactant for rapid uptake under a wide range of conditions. The benefits of MaxCel include:

  • Fruit thinning
  • Fruit size enhancement
  • Enhanced return bloom
  • Increased branching of nursery stock and young trees

Active Ingredients
MaxCel contains the plant growth regulator (PGR) 6-benzyladenine (6-BA), which stimulates shoot growth and bud break, as well as cell division.

How MaxCel Changed the Game
MaxCel contains 6-BA, a cytokinin that is used as a post-bloom thinning and sizing agent for apples and pears and for branching of nursery trees and young trees. 6-BA promotes cell division and fruit growth beyond just the thinning effect, resulting in enhanced fruit size at harvest. Because of its unique mode of action, MaxCel does not stress the tree or cause stunting of fruit, even with multiple years of use. MaxCel is a powerful tool used to adjust crop load, helping growers optimize their returns and ensuring annual cropping, while saving them money by reducing the need for hand thinning labor.

The effect of 6-BA on fruit thinning was discovered during the early testing stages of Promalin®, which is a combination of 6-BA plus GA4+7 used for apple fruit shape and quality. It was noted that high rates of Promalin caused a thinning response to some extent when the product was applied around bloom and petal fall. At first, it was assumed that this response was caused primarily by the gibberellins GA4+7, but soon after in the late 1970s, comparison studies clearly demonstrated that 6-BA was the primary thinning component.

Around the same time, due to the rapid adoption of new planting and training systems, 6-BA combined with GA4+7 was evaluated as an agent to stimulate lateral branch development on young apple trees. It was found that the high rates of 6-BA + GA4+7 used for branching frequently resulted in near de-fruiting of these young trees when applied late after bloom. As a result of these findings, it was concluded that 6-BA alone could potentially be used as a chemical thinner, as it causes fruit abscission, increases fruit size, and promotes return bloom.

Emergence of New Varieties
In the 1980s, new and more profitable fruit varieties were emerging at a fast pace. These new varieties presented novel thinning challenges for which existing technologies did not work. At the same time, retailers and consumers desired larger fruit, but growers were struggling to further increase fruit size with the available product options. Auspiciously, when 6-BA was used on its own, it was observed that 6-BA provided not only thinning benefits but also independent sizing benefits due to increased cell division.

All of these conditions, plus the discontinuation of the widely used blossom thinner sodium-4,6-dinitro-ortho-cresylate in 1989, created an environment where registration of 6-BA as a post-bloom thinner was widely supported. The formulation was challenging to develop due to solubility problems, but once this game-changing formulation was created, the first pure 6-BA product was registered in Australia as Cylex® in 1996. A few years later, the formulation was further refined and launched as MaxCel in the U.S. in 2004.

Formulation Expertise
While others have often tried to develop a similar formulation, they have never been able to demonstrate similar efficacy, which is a testament to the formulation skill inherent in developing the original product decades ago.

MaxCel has been on the market for more than 15 years, and the formulation’s features and benefits have been well-researched to deliver maximum value to growers. Today, MaxCel is available in all the main apple-growing countries around the world, proving its success as a trusted and efficient tool for growers on a global scale.