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Water Management

Proper watering of the trees will encourage an increase in growth of tree branches and in the production of quality fruit.

Tree Irrigation Needs

Trees need to be efficiently watered in order to make up for water lost through leeching and evapotranspiration otherwise they will produce less fruit as a result of water stress.

In order to properly determine how much water the trees need, it is important to know the evantranspiration, precipitation, water salinity, and application efficiency of the orchard.

Oftentimes growers cannot control the quality, quantity, and frequency of irrigation water in many areas, so it is important to know about the irrigation water before planting an orchard.

Some rootstock and scion varieties are easily affected by saline and drought conditions while others are better at thriving in these conditions. Seedling and clonal rootstock are better to be planted for land that has high salinity and drought conditions. This will ensure tree growth and prime fruit production.

Irrigation Efficiency

Using the water efficiently is important when there is little to use. The goal should be to maximize the water the trees receive from the irrigation. Irrigation delivery systems include drip, sprinkler, furrow and basin systems. Each of these systems has different efficiencies:

Type of irrigation system

Efficiency

Drip irrigation

90 %

Micro sprinklers

70-90 %

Furrow irrigation

60-75%

Flood irrigation

60 %

This means that when flooding an orchard, the trees will be able use only 60% of the water output. The furrow irrigation delivery system is the most realistic solution for Uzbek orchards. Efficient irrigation systems can help save money and resources when there is little water and it must be pumped.

 

Irrigation Systems

Irrigation systems are used to make sure the amount of water used on trees is used in the most effective way to help tree growth and fruit production. Irrigation systems help fruit production in many ways.

Irrigation systems help make sure that the same amount of water is being delivered to each tree so that the trees have similar tree growth and fruit production. Fertigation is a system where fertilizer and nutrients are dissolved into the water and delivered into the plant root system, aiding in tree growth and fruit production. Used effectively, irrigation systems can reduce the amount of water wasted. Sprinkler irrigation systems can help control frost in the spring and aid in tree and fruit cooling in the summer. Trees with efficient irrigation systems have been connected to higher quality and quantity of fruit than trees with normal irrigation systems.

Below are some of the main types of irrigation systems and their benefits and disadvantages.

 

Drip

Micro-Sprinkler

Sprinkler

Furrow

Flood

Efficiency

90%

80% – 90%

75%

60%

< 60%

Cost

Medium

High

High

Low

Low

Skill requirement

High

High

Medium

Low

Low

Filtration requirement

High

High

Medium

N/A

N/A

Wetted soil volume

Low

Medium

High

High

High

Salt management

High

High

High

Medium

Low

Frost control

NO

Medium

High

Low

Low

Cooling

NO

Low

Medium

Low

Low

Fertigation

YES

YES

YES

NO

NO

Broadcast fertilizer

NO

YES

YES

YES

YES

Supports cover crop

NO

NO

YES

YES

YES

Bicarbonate clogging

High

Medium

Low

N/A

N/A

 

Problem-free irrigation can only be ensured with regular check-ups of the irrigation system. Filters must be cleaned, main lines and lateral lines must be flushed to remove build up and acid flushed to remove other deposits. Filters and mainlines bust be drained before winter in order to protect water from freezing in the lines.

Water Problems

Lack of water

A tree will go through drought stress if it receives less water than it needs. Signs of drought stress are lifeless, yellow leaves, leaf fall before expected, and fruit ripening and dropping before the normal time.

Drought stress is often coupled with heat stress during months of summer when the temperature is hot. A result of the combination of drought and heat stress can be leaf scorching. This is when the leaves turn brown and the edges are dried out.

Rootstocks make a big difference in how well apple trees do in drought because of the differences in root growth. Trees with roots that are deep and trees on standard-sized and semi-dwarfing rootstocks, for example M.26 or MM.111, are better at dealing with short drought periods. Trees that have been freshly planted, young trees, and trees on dwarf rootstocks, like M.27 or M.9, have a harder time adapting to drought stress because their root zones are more shallow. Because dwarfing stocks produce more fruit per leaf area than semi-dwarfing stocks and standard-sized dwarfing stocks, transpirational water loss is more likely to occur and water is more easily lost during drought stress.

Excess of water

Too much water given to the trees can result in water stress or flooding. This can be just as harmful as drought stress. Because the extra moisture in the soil does not allow oxygen in the soil, the root system can be severely harmed. These roots can stop growing and refuse to take in minerals, leading to yellowed leaves and the inevitable death of the roots. Less fruit at poorer qualities will be produced prematurely as a result. The leaves will also begin to turn yellow starting from the crown of the tree and then spreading outwards.

Phytopathogen microorganisms can attack the root system of the tree when it is in this condition. Apple trees found in this situation often die slowly as the crown rots because of Phytophtora root and crown rot disease.

 Trees that have been found to be more water stress-resistant and  more resistant to Phytophtora root and crown rot disease are the dwarfing M.9 rootstock. The M.111 and M.7 rootstock have been found to be less resistant, and MM.106 even less so. MM.104 is likely to be impacted the most in regards to water stress, Phythatophtora root and crown rot disease.