applesApple growers get paid by consistently delivering large, top-quality fruit. But achieving this kind of fruit isn’t easy. Growers face a host of challenges including the environment, weather, economics, and traceability. Plant growth regulators are among the most valuable tools available to help growers manage some of these challenges. When properly used, these products can improve the fruit quality attributes: size, shape, color, finish and crispness. Equally important, they can extend the harvest window, allowing growers to take a systematic, block-by-block approach to harvesting their crop. A larger harvest window means fewer workers required to harvest the same area and less loss of fruit. And that means a better return on investment. Valent BioSciences’ products help growers meet production challenges in all stages of apple production.

Thinning and Sizing

It all starts with thinning. From the grower on through to the retailer, there is a huge price difference between small apples that get packed and sold in bags and big, beautiful apples that can be displayed and sold individually. To get those apples, growers need to thin their fruit. Too many apples on the tree results in small fruit size, poor quality and a reduced crop next year because of alternate bearing.

The most effective approach is with a plant growth regulator that thins fruit, such as 6-benzyladenine (6-BA). This is the active ingredient in MaxCel®; (known as Cylex® in some countries). MaxCel thins and reduces alternate bearing without stressing the tree or causing stunting of the fruits, even over multiple years of use. In fact, it also enhances return bloom, especially at higher rates. Fruit is more uniform as well, and pack-out and marketable yield are improved.

Thinning is only one way that PGRs are used to increase fruit size. MaxCel stimulates cell division and increases cell numbers, boosting fruit size beyond the direct thinning effect. This enhanced fruit growth is evident even under heavy crop loads. MaxCel’s one-two thinning/increasing fruit size effect make it a better choice than other thinners such as NAA (naphthaleneacetic acid).

Promalin® also contains the valuable 6-BA, but it adds two other PGRs, the gibberellins 4 (GA4) and 7 (GA7). These promote cell expansion/enlargement and elongation, also increasing fruit size. Promalin was first developed for use on Red Delicious to improve fruit shape (typiness) and increase fruit size. But its use has expanded greatly over the past several years as researchers identified new grower needs, variety mixes changed and new varieties have been introduced globally. Promalin use is holding steady on Red Delicious and is increasing on varieties such as Golden Delicious, Gala, Fuji, Pink Lady, Jazz and many others.

One of the newest uses for Promalin in the United States is to increase fruit set after a frost. In a recent study, it increased fruit set in Gala by 35% and in Jonagold by 70% – compared to untreated controls –following frost events. In effect, Promalinoffers freeze protection.

Promalin even promotes lateral branching in nursery trees.

Promalin followed by MaxCel has now become a significant and standard program in a wide range of varieties, including Gala, Fuji, Braeburn, Pink Lady, Jazz, Golden Delicious and Granny Smith.

Regulex® and ProVide® are additional helpful sizing products. They contain only the gibberellins GA4+7 which increase fruit size by increasing cell elongation. Regulex and ProVide are also widely used to improve fruit finish in russet-prone varieties.

Yet another way to increase fruit size is to allow the crop to remain on the tree. Aminoethoxyvinylglycine (AVG), the active ingredient in ReTain®, delays maturity, allowing fruit to grow longer and increase in size.

increased fruit sizing
VBC PGR Program for Apples
Enhancing Apple Quality with VBC PGRs
For growers, quality equates to profitability, and quality fruit is created with careful management throughout the growing season. VBC plant growth regulators enhance several key quality characteristics that boost the grower’s bottom line:
  • MaxCel thins the crop, increases fruit size and improves return bloom.
  • Promalin enhances fruit shape, size and finish.
  • ProVide and Regulex  reduce russet and improves fruit size.
  • ReTain delays maturity and enhances fruit storageability.  It reduces maturity related disorders such as watercore, stembowl cracking and greasiness. It also helps maintain uniform starch levels and fruit firmness.
  • One of the newest uses for Promalin in the United States to increase fruit set after a freeze. In a recent study, it increased fruit set in Gala by 35% and in Jonagold by 70% – compared to untreated controls – following frost events. In effect, Promalin offers frost protection.

Harvest Management

ReTain inhibits the biosynthesis of ethylene, and is used to slow the apple crop’s entire maturation process. Applying ReTain four weeks before anticipated harvest provides maximum protection against fruit drop – this is especially true when unfavorable weather such as high wind, excessive heat, or drought occurs prior to harvest. By staying on the tree for another week, apples have more time to grow, increase in size and to develop good color.

ReTain extends the harvest window for apples allowing growers to harvest more fruit at the optimal stage of maturity which maximizes storage potential

ReTain gives growers a tool to manage harvest more efficiently by letting them taking a block-by-block approach and synchronize harvest times with fruit maturity and labor availability. This reduces harvest peaks and the total number of pickers needed.

Bottom line: ReTain is a harvest management tool designed to help apple growers realize the full potential value of their apple crop through the improvement and maintenance of fruit quality at harvest and after storage.

ReTain is used globally on a range of varieties: Red Delicious, Golden Delicious, Royal Gala, McIntosh, Empire, Pink Lady, Braeburn, Fuji, Granny Smith, Honeycrisp and many others.

ReTain Treated: Reduction of pre-harvest fruit drop by slowing fruit maturation.
Untreated Significant fruit loss.