Should a grower bin his trees into cold storage and wait until rain or proceed to plant in this dry spell? This was a question received by email regarding planting of almond trees for 2014.
The concern is based on the point that most irrigation systems are not installed prior to planting due to interference with the planting crews. This prevents the ability to pre-irrigate to increase soil moisture at planting. Another concern is the speed of tree planting versus the speed of tanking trees, in which trees are often planted much faster than they can be tanked.
Although sometimes necessary, placing trees into bins and then into cold storage should be avoided if possible. Once trees are in bins, they begin root development, which is then disturbed upon removal and planting. This stunts the tree’s growth.
Trees should be planted as soon as possible when delivered from the nursery. This reduces the chance that any type of issues may occur (i.e. frozen bare roots, dry-out, etc). Trees should be kept moist, out of direct sunlight, and not laid out to far in advance of the planting crews. These steps help reduce dry-out, which can be an issue on peach-almond and complex hybrid rootstocks.
After planting of bare roots, the trees need to be tanked to settle the air pockets and provide a bit of moisture. Without the application of 3+ gallon of water around the base of the tree, air pockets that form from the planting process will inhibit the formation of roots, leading to poor growth. This is a time intensive process, but very critical especially when planting into heavy or dry soils. Tanking should still occur with potted trees, although the hole that is dug is often not as extensive and therefore the water amount may be reduced. Personally, I have seen several orchards start off with a lot of growth variability due to the omission of this step.
Once the trees are planted and tanked, the irrigation system should be installed as soon as possible. The time frame of installation is short: initial tanking will provide about 1-2 weeks of water after leaf out. At this point, trees will need to be irrigated with the installed system or re-tanked (unless we have rain).
To determine water needs, soil moisture needs to be checked around the newly planted tree – not several feet from a tree – as the developing root system is initially quite small. Irrigation of young trees is often best achieved by frequent, short duration applications of water. Preventing over- and under-irrigation is a balancing act, but moderate levels of water stress will slow and high levels will stop the growth and development of a young tree.