Long-Term Changes in Rust Incidence

Only four States have rust data from three surveys, so only a limited analysis of long-term changes in rust could be made. In the four states--Mississippi, North Carolina, South Carolina, and Virginia--there was a slight upward trend in the number of planted and natural acres of slash and loblolly pines (fig. 3). The trend for loblolly is much stronger than for slash pine (figs. 4, 5). Acreage with >10-percent rust infection increased from the 1970's to the 1980's (but only slightly in Virginia, where rust incidence is uniformly low) but decreased during the 1980's to the early 1990's (fig. 6). This was true for each species (figs. 7, 8). Magnitudes of change in infected acres between earlier and later surveys were not particularly different, although they, too, were highly varied (tables 9-14). For instance, the number of planted slash pine acres with >10-percent infection in North Carolina increased 32 percent from 1975 to 1984, while the number of planted loblolly acres in South Carolina with >10-percent infection decreased 9 percent over the same time span. Although data with rust incidence is not available from the 1970's for other than these four States, these trends may well represent much of the rest of the South.

Figure 3. - Planted and natural slash an loblolly pine acreage, estimated from Forest Inventory and Analysis data for four states.

[ top ]

Figure 4. - Planted and natural slash pine acreage, estimated from Forest Inventory and Analysis data for three states.

[ top ]

Figure 5. - Planted and natural loblolly pine acreage, estimated from Forest Inventory and Analysis data for four states.

[ top ]

Figure 6. - Acreage of loblolly and slash pine with > 10-percent fusiform rust infection, estimated from Forest Inventory and Analysis data for four states.

[ top ]

Figure 7. - Slash pine acreage with > 10-percent fusiform rust infection, estimated from Forest Inventory and Analysis data for four states.

[ top ]

Figure 8. - Loblolly pine acreage with > 10-percent fusiform rust infection, estimated from Forest Inventory and Analysis data for four states.

[ top ]