Any year due to our regular drought cycles, the lack of sufficient rainfall and the very hot temperatures will cause a lot of die back on various trees and shrubs. If you are seeing brown leaves or discolored leaves on any of your plants then check your watering. If you have not been watering then START!! If you have been watering and find the soil dry, obviously, you are not watering enough OR you are watering incorrectly.
If you have allowed the soil to become very dry the plants may be at critical drought stage which means they are going to start dying or, at the very least, they will begin to lose leaves, stems and branches. Conifers, such as the Leyland Cypress, will begin to lose needles especially on the inside of the plant. Other trees may develop strange variegation on the leaves or just brown leaves before the leaves fall off the tree. Shrubs will just completely fail, losing all their leaves very suddenly. Trees and shrubs also become more susceptible to pest attack when they become stressed. Disease development increases as does insect and mite activity. Consequently more pesticide must be used to correct problems that were preventable simply by watering. Oftentimes, diseases that we have no treatments for start during stressed periods.
We have preached for years that you only need to deep water 1x per week to maintain your landscape. This will generally get your plants through the worst droughts but every yard is different. You may need to water less or you may need to water more. The key is to never allow your soil to become excessively dry. Trees require 5 gallons of water per each inch of trunk diameter per week. For example, a 5″ diameter tree would need 25 gallons of water per week. Your shrubs require at least 1″ of water per week. Measure your irrigation output with a rain gauge. Use 5 gallon buckets or Treegator® to water you trees.
During excessively hot and dry conditions you may need to water deeply two times per week to counteract increased evaporation and increased plant transpiration (water loss through the leaves). Again, if the soil is dry then WATER!
If you have allowed the soil to become dry, do an initial heavy watering to ensure the soil is adequately hydrated then you can move to the 1 time per week/1 inch per week regimen.
