The Hidden Factor That Could Be Sabotaging Your Tree Care Investment: Water pH and Its Impact on Treatment Success
When homeowners invest in professional tree care treatments, they expect results. Yet many are unaware that a simple factor—water pH—can dramatically impact the effectiveness of tree spraying applications. Most pesticides break down faster in alkaline water and are generally most effective when mixed in acidic water, with the pH of water adversely affecting the performance of some pesticides in the spray mixture soon after mixing, resulting in less chemical applied and less control than expected.
Understanding pH and Its Critical Role in Tree Treatment
pH is the measure of acidity or alkalinity of solutions, using a scale of 0-14 to indicate whether the solution is neutral (7), acidic (0-6) or alkaline (8-14). For tree care professionals and homeowners alike, this measurement is far from academic—it directly affects treatment outcomes.
Spray water qualities such as pH can influence herbicide performance and may need to be amended for optimum weed control, as water quality factors can affect herbicide activity by reducing solubility, enhancing degradation in the spray tank, or forming herbicide-salt complexes with mineral cations, thereby reducing absorption, translocation, and subsequent weed control.
The Science Behind pH Impact on Tree Treatments
The chemistry is straightforward but crucial. The breakdown of pesticides is caused by a reaction called alkaline hydrolysis, and this reaction is affected by pH, with most pesticides breaking down faster in alkaline water and generally being most effective when mixed in acidic water.
The timing factor is equally important. Leaving the spray mixture in the tank overnight or for the day due to inclement weather can result in some pesticides breaking down, so pesticides should be applied soon after mixing in the spray tank and mixed pesticides left in the spray tank overnight should be avoided.
Consider this dramatic example: At pH 5, flumioxazin is very stable and will persist in water for several days, but as pH increases to 7 the half-life decreases to approximately 24 hours, and at pH 9 the half-life is a mere 15 minutes. This means treatments mixed with high-pH water could lose most of their effectiveness before application is complete.
Optimal pH Ranges for Maximum Treatment Effectiveness
In general, pesticides are most stable when the spray solution has a pH of about 5, though most cases show herbicides, insecticides, and fungicides tend to perform best in slightly acidic water with a pH range of 4 to 6.5. However, there are important exceptions to consider.
Other herbicides like RoundUp, 2,4-D, and Liberty tend to perform better at acidic pH ranges, while basic pH can be good for some herbicide products within group 2 – ALS inhibitors and group 14 – PPO inhibitors.
Testing Your Water: A Simple Step with Major Impact
Fortunately, testing water pH is straightforward and affordable. Check the pH of the spray water from any water source frequently throughout the season using indicator paper or a pH meter to check water pH. The fastest way to determine the pH level of water is to test it with a pH meter or test paper, though paper test strips are the least expensive, they can be unreliable and can vary by as much as two pH points, while a pH meter will provide the most reliable and consistent readings.
For homeowners, a faster and cheaper way to determine the pH level of water is to use test paper, however, paper test strips can vary by as much as 2 pH points, while a pH meter will also provide fast results with more reliable and consistent readings, with meters that measure pH within 0.2 points of accuracy available commercially for as little as $50.
Solutions for pH Problems
When water pH is too high, several solutions exist. A pH of 4 to 7 is recommended for mixing most pesticides with a value of 5.5 to 6.5 being ideal, and if your spray rig will be left to stand for several hours before the contents are applied, consider adding an acidifying agent to prevent alkaline hydrolysis.
Granulated food grade citric acid may be the most convenient and inexpensive acidifying material and is available in 50-pound bags from suppliers that handle food grade chemicals, with two ounces per 100 gallons shown to reduce the pH of tap water from 8.3 to 5.4.
Commercial buffering agents are also available. Some buffering agents such as pHase5 or PHT indicate five will have a color indicator when the correct pH is achieved, where growers can add this product into the water until it reaches the color that indicates a given pH, for example, five = pink or red; six = orange; etc.
Professional Expertise Makes the Difference
While understanding pH is valuable for homeowners, working with experienced professionals ensures optimal results. Jones Tree & Plant Care, serving Suffolk County, NY, demonstrates this commitment to excellence. As a licensed arborist, Jones is committed to offering scientifically based landscape management and delivering quality services, with Jones Tree and Plant Care inspecting landscapes, diagnosing problems, and making recommendations based on knowledge and expertise gained through over 10 years of experience in the industry, while as a certified arborist, Jones receives continuous education and instruction, and is always up to date on the latest trends and techniques.
The company’s approach reflects industry best practices. Jones Tree and Plant Care tailor specific programs based on the needs of each individual customer and property, with a total tree and plant care approach improving growth, condition, and curb appeal of properties, all while using environmentally sensitive, affordable treatments.
For homeowners seeking professional tree spraying services, this attention to detail—including water quality considerations—can mean the difference between successful treatment and disappointing results. Jones Tree and Plant Care offers organic programs that promote outstanding land stewardship based on the ecological principles of nutrient cycling, biotic regulation of pests, and biodiversity, advocating safe, healthy property management using organic and the least toxic practices and products that nurture and protect the health of families, pets, wildlife, and the environment.
Taking Action for Better Tree Care Results
Don’t let poor water quality undermine your tree care investment. Spray water quality is a manageable factor that, when addressed properly, can help maximize herbicide performance and ensure more consistent weed control throughout the season, and for help testing your spray water or choosing the right adjuvants for your program, contact your Local Extension Educator or crop consultant.
Whether you’re a DIY homeowner or working with professionals, understanding and addressing water pH is a simple step that can dramatically improve treatment effectiveness. Water pH is affected by temperatures, sunlight, rainfall, drought and many other factors and is seldom the same from one spraying to the next, therefore, check water pH before each pesticide or growth regulator application.
By paying attention to this often-overlooked factor, you can ensure your tree care treatments deliver the results you expect and deserve.