Photographs taken during the 1976 cotton-growing season ware analyzed
Photogrammetrically for a number of cotton fields, and the percentage of land Area diseased with Phymatorrichum root Rot was determined.
Cotton fields were located and identified by signature form Photographs covering all of Falls County.
Idenification was verified by ground-truth surveys of Actual conditions,especially in areas of questionable identity .
Cotton field identification was Enhanced by photographs taken 24 August 1976 after harvest of grain sorghum , leaving Cotton as the only row crop.
Cotton acreage in the county was measured by transferring Boundaries of field areas from a 1:120,000 scale to a 1:24,000 scale, using 7.5-minute USGS Topographic quadrangle maps. The area was then computed with a planimeter.
Percentages of field areas diseased were ascertained from 1:20,000 scale Photographs.
Dot grids were projected onto the field photograghs with a Bausch and Lomb Zoon Transfer Scope,
And the From photgrammetric analysis (13) (Table 1).
Areas infested with Phymatotrichum Root rot were usually considered total losses because the easity uprooted infected cotton Plants and unopened bolls jammed harvesting equipment.
For calculating the disease’s Economic impact on cotton production,infested areas were considered total losses.