Rather than simply identifying a potential problem (FMD) and a solution (inoculation), Deasy's letter sets the stage with a grand consideration of Irish economic history, past present and future. A thread of conspiracy-mongering runs through it all, and after Stephen finishes reading the letter, Deasy tells him that conspiracies are thwarting his own efforts to call attention to the FMD problem: "I am trying to work up influence with the department. Now I'm going to try publicity. I am surrounded by difficulties, by... intrigues by... backstairs influence by..."
The "department" is presumably the "department of agriculture," described in the letter as displaying "pluterperfect imperturbability" in the face of alarming information. Only God, or Joyce, knows exactly what Deasy may mean by it, but the general sense seems to be extreme indifference. "Pluterperfect" sounds like a neologism, but Katherine Schwarz points out in a personal communication that "the current online version of the OED has found earlier uses, both in the grammatical sense (same as pluperfect) and the figurative sense as 'utterly perfect' (also same as pluperfect). They explain its origin as 'Apparently an alteration of pluperfect adj., after preterperfect adj. However, compare earlier pluterpositively adv.'" Ellmann observes that "Joyce is parodying not only Blackwood Price but himself.... The word 'pluterperfect' he borrowed from his earlier essay, L'Ombra di Parnell, where the Italian equivalent is 'piuccheperfetto'" (327n). He liked the phrase enough to use it again in Oxen of the Sun, where the imperturbability belongs to a God who happily devours human bodies.
Deasy would like the imperturbable department to consider the potential impact of FMD on "our cattle trade," which (if prompt action is not taken) may go "The way of all our old industries." The demise of many of these industries is lamented by the Citizen in Cyclops. He thinks of a scheme in the 1850s and 60s to make "Galway harbour" a translatlantic port housing a Galway-Halifax steamship line, and of a "Liverpool ring" which allegedly sabotaged it to protect its own shipping interests. Citing Robert M. Adams' Surface and Symbol, Thornton concludes that there is no evidence of any such conspiracy and "Deasy is mistaken again." Gifford summarizes the sorry history of the project and concludes that "the evidence, on the contrary, points to the maritime incompetence of the promoters." Looking forward in time, Deasy predicts that a "European conflagration" (one would erupt in 1914) might disrupt shipping of "Grain supplies through the narrow waters of the channel" separating Ireland from England and Scotland.
It is not certain what exactly these disasters past and future may have to do with "That doctrine of laissez faire which so often in our history...," but presumably Deasy is urging the Department of Agriculture to adopt a proactive, interventionist policy, rather than passively waiting for foreseeable problems to wreak havoc on the economy.