The third oxamyl application of the trial occurred on March 24 and soil samples were taken on 1 May. As reported previously, the sting nematode populations remained low in this grove (<10 nematodes/250 cm3 soil), and it was not possible to distinguish significant treatment differences, although average population density during the past year was 47% lower in plots treated with oxamyl in the uncovered trees and 23% lower in the plots with IPCs. Fibrous root density in May was unaffected by nematide application in either covered or uncovered trees. It is noteworthy that prior to the trial, in January 2022, when the orchard was replanted, 20 trees throughout the block were pulled to examine the root systems (Fig. 1 in the attached word document). Every tree had an extensive surface root system with varying amounts of fibrous roots; however no tree had roots deeper than approximately 12 inches and every tree exhibited extensive sting nematode damage at about the 12 inch depth. In other words, sting nematode damage was severely limiting the depth of the root systems. Moreover, the measured sting population density throughout the block was an order of magnitude larger at that time than since the block was replanted and this trial began. Rootstock may be affecting sting nematode density in the trial. The rootstock US 812 was introduced in the grove when it was replanted in 2022. A CRAFT roostock trial in an adjacent grove includes a number of USDA and UF rootstocks, and sting nematode populations measured in that trial several years ago showed US 812 to have the lowest number of nematodes of the rootstocks in the trial. US 812 was also among the top two performing rootstocks in the ongoing greenhouse tolerance trials and will be evaluated a second time in combination with UF and other USDA rootstocks a trial that will terminate in October 2023. In an ancillary project, initiated in this grove at the same time as the current IPC-nematicide trial, we are evaluating an unregistered nematicide produced by Syngenta. The trial is being conducted in the same manner as the IPC-nematicide trial (spring and autumn applications followed by summer and winter assessments), but without any protection from HLB. The Syngenta material was the best-performing of four new nematicides tested in a previous CRDF trial to control sting nematode. The new chemistries are much safer to use than traditional nematicides, have high toxicity to nematodes but very low toxicity to mamals birds and fish. Moreover, the recent availablity of several new nematicides will allow rotation of chemistries with different modes of action to help prevent loss of efficacy due to nematode resistance development or the development of accelerated microbial degradation. The new product is being tested at low and high rates (L and H), with and without an adjuvent (S), and with applicatons either once a year in spring (S) or twice annually in spring and fall (F). To date the new nematicide has performed consistently as well as or better than oxamyl against sting nematode (Fig. 2 in the attached Word document), albeit under conditions of relatively low population density in this grove. All treatments have measured efficacy ranging from 57% to 90% against the nematode. On May 14 the following rootstocks were planted into the tanks infested or not with sting nematode and will be harvested in 20 weeks to comprise the third tolerance trial: UFR 1, UFR 5, Orange 16, MG 11, CB8-9xS13-15-16, S10x639-12-32, US 812, US 942, US 802, US 1284, US 1283, US 1516, Swingle, Kuharske, Sour orange, Sweet orange.