Technical update on branching strategies in cherry orchards

1. Branching strategies

Obtaining a high number of lateral branches in cherry trees is essential to bring forward the onset of production, promote the formation of fruiting centers and fully express the productive potential of each variety.

This intervention must be carried out during the second year after orchard establishment, since the onset of production in the third year depends on it.

Poorly branched trees delay the onset of production and never reach their full productive potential. It is therefore necessary to promote the formation of the greatest possible number of branches.

All branching treatments are temperature-dependent: in the days following the intervention, they require temperatures above 13 °C, which are necessary to accumulate heat or degree-days and allow the development and growth of shoots induced by growth regulators, i.e. synthetic hormones applied exogenously (CK: TDZ, 6-BA; GA3, GA4 and GA7).

Growth regulators

The use of higher doses of growth regulators, such as Promalin, Splendor or gibberellic acid, does not necessarily result in a greater number of shoots. On the contrary, excessive concentrations can easily cause phytotoxicity affecting buds or shoots.

To achieve efficient and satisfactory branching, it is necessary to follow the methodology described below.

1.1 Use of hydrogen cyanamide

Hydrogen cyanamide, such as Dormex or Cianamida 50, must be applied with a backpack sprayer at a rate of 1.5 L/100 L of water (1.5%), mixed with Silwet TX 100 DC at a rate of 20 cc/100 L.

The treatment must cover the area to be branched, starting 70 cm above the ground and extending up to 30 cm below the apex of the central leader. In later areas, application must be carried out between July 25 and August 1.

Product dripping must be avoided, and treatment should be carried out at temperatures above 8 °C to prevent phytotoxicity. This results in more uniform bud break and simplifies subsequent notching operations associated with the application of Promalin or the brushing of buds with thidiazuron and gibberellic acid (GA3).

Cherry orchards planted during the previous winter must undergo branching during the following season. Branching must therefore be stimulated or forced from the phenological stage of red-tip bud through to the green-tip bud stage.

Treatments to force branching

Below are some treatments useful for stimulating the formation of new lateral branches.

Treatment 1: cherry tree branching through notching and Promalin

• Make the cut exclusively at the phloem level. The notch must be made 1 cm above the bud using a serrated saw.
• Create levels consisting of four notches each, spaced 30 cm apart along the leader, starting 70 cm above the ground and extending up to 30 cm below the apex of the leader or leaders of the tree.
• Using a toothbrush, generously apply the mixture of Promalin and latex to the notched area.
• This treatment is not recommended in the southern areas of Chile, from Chillán southward, due to greater disease pressure, particularly bacterial canker.

Treatment 2: brushing the buds without notching

• Apply the mixture generously directly onto the bud, without making any notches. Before application, the mixture must be mixed very thoroughly.
• Treat as many buds as possible. It is very important not to apply the product twice to the same bud.
• Gibberellic acid must be used in powder formulation to avoid phytotoxicity phenomena that may occur with products in liquid formulation.
• This strategy depends more heavily on the accumulation of heat required to induce branching and therefore requires a warm spring.

Bud-brushing procedure to force cherry tree branching

Treatment 3: alternative branching technique for southern areas

For branching in cold areas, from Temuco southward or in foothill areas, a treatment without notching can be adopted as an alternative to the use of Dropper.

Mix the mixture very thoroughly before application.

Using a brush, treat the section of the trunk that is intended to branch. Proceed from bottom to top, in an acropetal direction, to avoid damaging the buds and causing phytotoxicity due to excess product.

It is very important not to apply the product twice to the same bud.

Shoot development using branching treatment 2

Toothpick positioning

After branching, toothpicks must be inserted at all the shoots obtained, in order to correctly define the opening angle of the future branches in relation to the central leader.

The operation must be carried out when the shoots have reached a length of between 15 and 20 cm.

Image source: Agro Asesoria

Patricio Morales
Agro Asesoria

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