Plant Disease as a Driver of Land Use Change: Evidence from Citrus Greening in Florida

Catastrophic crop diseases are widely assumed to accelerate the conversion of farmland to urban uses, yet rigorous causal evidence on the destination of land released from agriculture is scarce. We use the spread of huanglongbing (HLB), or citrus greening, in Florida as a natural experiment to estimate where land flows after a severe and persistent productivity shock. Combining USDA National Agricultural Statistics Service citrus surveys with the annual USDA Cropland Data Layer for the period 2008 to 2023, we construct a county-level yield-loss proxy for HLB severity and exploit two complementary identification strategies: a within-Florida two-way fixed effects design across fourteen citrus counties, and a matched difference-in-differences design that uses California citrus counties, which were largely unaffected by HLB during the sample period, as a counterfactual. We find that a one-unit increase in the production pressure due to HLB is associated with a 28 percent annual decline in citrus acreage and a meaningful reallocation of land toward forest and shrub cover (1.7 percentage points) and lower-value agricultural uses (0.7 percentage points), with a small and generally insignificant effect on developed land. The matched differencein-differences design corroborates this pattern: treated counties lost 3.8 percentage points of citrus share after 2012, while developed land grew by less than one percentage point. Results are stable across robustness checks that include house price controls, climate covariates, and the exclusion of hurricane years. A complementary analysis suggests that depressed land values in former citrus counties may have facilitated utility-scale solar development after 2016. The findings indicate that even severe and incurable plant disease shocks generate land-use adjustment primarily within agriculture and toward natural reversion rather than urbanization, with implications for farmland protection policy, rural development, and the design of disease-response programs.