I have had many inquiries about applying an irrigation since we have been lacking adequate (if any) rainfall. At this time of the year, with bloom 5-6 weeks away, the answer is “yes.” As bloom approaches, it is important to have adequate moisture within the soil to a depth of at least 30 inches to promote root growth during the first root flush. Research in peaches suggest that this first root flush occurs about two weeks prior to bloom.
Irrigation sets should not last longer than 24 hours and should target around 0.5 – 0.75 acre inches of applied water. After the application, the water should have time to infiltrate the soil, about 3-4 days, before the next irrigation is applied. Following these practices will help reduce the saturated soil conditions that favor soilborne diseases such as Phytophthora. After each irrigation, check the depth of the added moisture. Once moisture reaches four to five feet, application of water can be discontinued. Rainfall will only help refill the soil profile. Keep in mind that at this point, we will need more than five inches of rain to refill the moisture in most soils without supplemental irrigations.
If it rains within the next two weeks, irrigate before the rain event with another 0.5 to 0.75 inches. This will help increase the effectiveness of the rainfall. If there is no rain in the two weeks, plan for another irrigation.
This may be a good time to apply a pre-emergent herbicide. An irrigation will “water in” the herbicide, but the effect will be limited to the wetting pattern of the irrigation system.
Four weeks ago, the answer to this question was a “no.” Attempting a poor excuse for why I changed my mind — I thought we would have received some rain by now.