We spoke with both cherry production specialists regarding the accumulation of Chill Hours; here is what they told us:
We are experiencing an autumn period with very low temperatures, which is very good news. How do you project the accumulation of cold hours due to this event?
Carlos Tapia: «I don't dare to say projections, because obviously there is a question of climatic evolution. However, we are optimistic about the quality of autumn. The end of April and beginning of May are cooler and that in one way or another encourages and attributes to a greater acclimatization of the plants, which is undoubtedly much more beneficial in terms of dormancy.»
In your opinion, and with a very cold autumn, how do you see the accumulation of cold hours occurring, with the crop practically entering into full dormancy?
Ricardo Minho: «It is coming out much better, much more positive. I have also been able to see a very good quality of the buds, but I totally agree with other specialists such as Carlos Tapia, that there are fewer shoots. Especially in varieties that last season had a more or less normal load, I am referring to the Lapins. You have to be careful, because many of the shoots come with no or very few fruit buds.. It looks like a very auspicious season, with a very good accumulation of cold and with serious risks of early frosts in spring, so we have to be careful.
Green tips at this time of year and frost
Carlos Tapia: «During this period, the orchards should show, in addition to a significant percentage of yellow leaves, which ideally reaches 50 percent by May 1, fruit centers with well-closed and lignified shoots and bases of twigs, with their bracts very well formed (Image 1); it is not ideal, but in the worst case it could occur, to appreciate the outline of green tips, a situation that should not represent major inconveniences. Contrary to this, during this period open shoots or green buds with a good percentage of green tips or almost ready to open should not be appreciated. (Image 2).
Ricardo Minho: «Normally, this type of phenomenon is associated with a particular problem in the orchard, in terms of management or irrigation, which may have occurred early or during February, which was too warm. There are many orchards that were not able to measure the increase in temperatures that occurred during this month, therefore they were not able to regulate irrigation, and also associated with some nutritional imbalance, which led to us finding these green tips today. Now, if these green tips are associated with a poorly closed bud, it is a serious problem.»
What impact could this have on the accumulation of cold hours in the crop?
Ricardo Minho: «Mainly, a poorly closed bud or one with obvious green tips is a much more sensitive bud. In addition, we are already having frost events and we will surely have stronger events and those buds that were poorly closed or with these green tips, the bud analysis will surely show that there are damaged primordia and obviously we will reduce our floral supply, which also makes the determination of the use of cyanamide or homogenizers much more delicate, because the sensitivity increases for all these types of products.»
Carlos Tapia: "This poses a problem from the point of view of production potential, which could be affected by early frosts; in addition, from a health point of view, it reverses a high risk of bacterial cancer and wood fungi, such as Cytospora, which has been more present in the fields in recent times, especially in colder and southern areas."
