What management measures should be taken after grafting walnut trees?

Management techniques

(1) After grafting: check for survival after about 10 days. The signs of survival are the leaf petiole falling off or the bud sprouting. Re-graft promptly those that have not survived.

(2) Removal of sprouts: remove the sprouts on the rootstock to promote the sprouting of the grafted bud. Generally, remove sprouts once every 10 days or so.

(3) Cutting the rootstock: once the grafted bud has survived, cut off the rootstock about 2 cm above the grafted bud to stimulate the growth of the grafted bud.

(4) Unbinding: when the new grafted shoot has grown to more than 5 cm, the wrapping can be untied. Unbinding too early or too late will both affect growth.

(5) Pinching: when the new grafted shoot has grown to about 30 cm, pinch off the growing tip to help it survive the winter safely.

(6) Pest control: if pests such as the mulberry looper and slug moth occur, they can be controlled with a 2000-fold dilution of fenvalerate.

(7) Cold protection: walnut trees grafted in the field in the same year need winter cold protection. Before the soil freezes, those that can be bent down should be covered with soil for cold protection; those that cannot be covered with soil can be wrapped with plastic film. In the spring of the following year, uncover them from the soil or remove the wrapping at the appropriate time during the sprouting period.

Precautions

(1) Field grafting of walnut uses green shoot scions. It is best to collect scions nearby and graft immediately after collection. If scions need to be transported or stored for a short period, moisture preservation must be done well.

(2) The grafting site should be selected on branches less than 3 years old. If the grafting site is too thick and the cortex is too thick, the survival rate will be affected.

(3) For grafting on larger rootstocks, shape the tree first and then graft. The bud pieces should be grafted on both sides of the branch to help open the branch angle and improve ventilation and light penetration.

(4) The grafted buds must be relatively plump leaf buds or mixed buds. Male flower buds cannot be used as scions. Using shriveled buds as scions generally means they will not sprout in the same year.

(5) Grafting operations should be quick, and the wrapping should be tight.

(6) Pay attention to listening to weather forecasts and try to avoid rain after grafting, so as not to affect survival.