This July 31st the accumulation of cold hours officially ends and the cherry orchards begin to “wake up”, giving way to the phenological states, which range from dormant bud to maturity and which are very well explained in the Guide to the main phenological stages of sweet cherry in Chile prepared by the Pomanova Corporation.
Although frost episodes are constantly recorded during the winter period, it is from the swollen bud phenological stage (considering the month of August) when special emphasis must be placed on controlling them, because during the initial phenological stages, temperatures below -0.5ºC for more than an hour could cause damage to the plants.
“With the increase in temperatures, plants begin to move, as a new season is about to begin in terms of temperature accumulation; during this time we are not exempt from concerns, since from August, coinciding with the phenological state of swollen bud, the sensitivity to frost damage in the species increases. We have detected that we have greater sensitivity to damage from the phenological states of swollen bud to exposed bouquet and not after exposed bouquet until petal fall or jacket fall, which from the point of view of the dates it is unlikely that we will have frost events”, said Carlos Tapia, specialist advisor in cherry production and Technical Director of Avium.
Although for several years in our country it was thought that frosts were more risky the more advanced the phenological state was, various investigations and practical examples have shown that sensitivity to damage is greater between swollen buds and exposed bouquets, which is why it is essential to begin frost control before the swollen bud stage.
In the face of the aforementioned climatic episodes, it is essential to have frost control systems in orchards, in order to avoid frost damage that occurs when ice forms inside the plant tissue.
Frost can cause the same damage to various fruit species, however the consequences of freezing will depend on the phenological state of the plant when the climatic episode occurs.
“Our first concern, in this first stage of the phenological states from swollen bud to exposed bunch, is to be alert and have the frost controls that we have in each of the orchards “ready”, both frost control by water, by wind or the use of helicopters and obviously the use of tents, which although not a frost control model, help us to protect the temperature under the tent and avoid slightly milder frosts (-1.0 to -1.5ºC) in a short time. So from August 1 to 10, we get a little more nervous and we start to worry about these issues that could well be influential in a season of low temperatures and that could affect, in some areas and in some varieties, compromising production a little more”, Tapia concluded.
