I’ve only lived in Houston for seven or eight years, but this past summer was wetter than any I’ve experienced. It seemed like a complete reversal from the brutal drought of the previous year, with fairly moderate temperatures, and such surprisingly regular rainfall that I didn't need to irrigate nearly as much. Unfortunately, the rain and high humidity also resulted in increased incidences of fire blight, black sooty mold, and wooly whitefly, and my sprayers seemed to exacerbate these problems even further. Most of my sprayers worked wonderfully for those trees with a well defined single trunk (like the apple trees), but they sprayed directly into the foliage of lower bushy trees such as the citrus, creating conditions ideal for the growth of black sooty mold and other pests.
After reviewing several options, I decided to convert my irrigation system from sprayers to drip emitters. Fortunately, I was able to find a screw-on adapter that fit my 1/2-inch risers. I started changing out all the heads, when I remembered why I had installed sprayers in the first place: I ran over my homemade drip system (a garden hose with holes drilled in it) with the lawn mower. Further more, every time in the past when I have placed a dripper or a soaker hose on the ground, it quickly became clogged. So my challenge became to find a way to irrigate my trees that 1) wouldn't spray into the leaves and make disease/pest problems worse, 2) wouldn't get shredded by the lawn mower, and 3) wouldn't get clogged up with dirt.
The answer? Hang drip-lines in the trees! from each riser I ran a drip-line with 10 0.5-gallon/hour emitters, and coiled the line around the trunk in the lowest branches of the tree. This would ensure that water would be delivered where I wanted it without clogging, I wouldn't be spraying the foliage, and the lines wouldn't get pulled into the mower. I chose to use 10 emitters per tree just to make irrigation calculations easier: 10 0.5-gallon/hour emitters running for 1 hour = 5 gallons of water per tree. I must say, I'm very impressed with how well it works so far. Now when I turn the dial, it looks and sounds like it is raining, but only under the trees! By adjusting the way water is delivered, and by spraying alternating applications of neem oil and spinosad, I am very hopeful that diseases and pests will be much easier to manage this year.