The summer of 2016 is in full effect. We are racking up the 90 degree days, and our landscapes are beginning to suffer as a result. Insect populations are high with record numbers of Japanese Beetles, aphids, and mites showing up this season. The combination of insect damage and heat stress is enough to frustrate any homeowner, but this season started with cool and wet conditions so various fungal and bacterial diseases are adding to the stress our plants are dealing with. With such difficult conditions, it may not be possible to eliminate all plant stress. Our focus moves to managing stress and treating symptoms to allow plants to get through a few more tough weeks.
Proper irrigation is the number one way to limit plant stress. It is important to tweak your irrigation system throughout the season to adjust the run time, frequency, spray pattern and time of day that the system will run. It is important to understand the soil drainage around your property. Over watering in areas where drainage is poor can lead to saturated soils that will not allow roots to grow. Under watering in areas with good soil drainage will lead to dry soils and plant stress. The time of day that your system runs is also key in preventing plant stress. Watering in the evening hours can promote foliar diseases like powdery mildew and leaf spot. These diseases thrive when the leaf surface is wet and temperatures are in the 60’s overnight. Setting your irrigation system to run in the early morning hours puts water in the soil as the sun rises and root systems become active.
Addressing insect populations will also decrease plant stress. This can be achieved through changing plant material and pesticide treatments. Monitoring insect life cycles will allow for the best use of pesticides when insects are most susceptible. Changing plant material may seem like an extreme strategy, but removing plants that attract various pests can help the overall health of the landscape. For example, removing areas of overgrown Virginia creeper can reduce the attraction for Japanese Beetles.
Evaluating the landscape as a dynamic system is key when making decisions. It is very important to look at all aspects of the landscape such as soil structure, irrigation capability, sunlight exposure, plant species, insect and disease pressure, and soil nutrient load when deciding what actions will result in the highest level of plant health.