Soil samples were taken on November 27 and the majority of IPCs removed due to tree size. Leaf samples were collected from all trees and sent to SWREC for HLB determination (pending), trunk diameters and tree heights were measured. Nematodes and fibrous roots were recovered from the soil samples. The IPCs increased (P<0.001) the fibrous root weight more than two-fold (0.115 vs 0.055 mg/g soil), the 12-month growth of trunk girth by 81% (662 vs 365 cm3) and 12-month increase of tree height by 3-fold (19.8 vs 6.5 inches) compared to non-covered trees. Vydate had no significant effects on the tree growth in 2023 although root weights were 20% and 14% greater, and trunk girths 7% and 6% greater in IPC vs non-covered trees, respectively. To date, the cumulative sting nematodes were reduced by just 30% during this trial which is not typical of other reports of trials we have conducted. A difference between this and previous trials is that we generally apply Vydate to trees in small plots using handheld sprayers or herbicide applicators. Here, the material is injected into dedicated irrigation lines and distributed via microjets. In October we tested the hypothesis that the distribution of chemicals applied via microjet is significantly less uniform than if sprayed directly on soil. Sodium bromide was applied under 3 trees via micro-jets and soil collected at different depths and distances from the emitters, immediately and periodically for one week. The bromide was leached from the soil samples and measured. Analysis of the chemical distribution is ongoing, but a second trial measuring the deposition of water and entomopathogenic nematodes (EPN) in the wetted zone during a one-hour irrigation period is informative (Figure 1; see MS Word document). The water/EPN deposition was measured by placing canisters at different distances and directions from the emitters on several trees. Soil at distances of 1 or 5 feet from the emitter received 75% less water than at 3 feet. The deposition of EPN was even more skewed than that of water because (as with chemicals) they were injected during about 15 minutes of the hourlong irrigation cycle and had less opportunity to recover from wind directional changes. These plots were partially covered by tenting plastic sheeting over the trees; the variability would be more extreme in an open field. The data suggest that there is greater opportunity for nematodes to avoid encountering a fatal dose of the nematicide in soil treated with micro-sprinklers than with a directed spray pattern from equipment such as herbicide applicators. The project continues and will evaluate effects of water pressure and emitter configuration on the deposition patterns. The effects of the Syngenta product were also measured during this quarter. The overall suppression of sting nematodes was unaffected by an adjuvant and so the treatments with and without adjuvant were combined for analysis. When the high and low rates were applied once annually in the spring, sting nematode cumulative density during two years was reduced by 55% and 36%, respectively, compared to controls, but the differences were not significant. When the high rate was applied twice annually (in spring and fall), the sting nematodes were significantly reduced by 74%. Again, the Vydate reduction (37%) was not significant.