Littleleaf Disease on Loblolly Pine: A Selected Bibliography

Littleleaf disease is a site and pest complex. This disease complex destroys the ephemeral, absorbing root fans of large pines on heavy clay soils. The primary causal agent is the root rot fungi Phytophthora cinnamomi, although other soil pathogens play a role. Littleleaf is a disease of mature / overmature pines on eroded, compacted, and poorly drained sites with little or no effective A horizon containing organic matter. Symptoms are often mis-identified as a nutritional problem. Symptoms include needle yellow-ing, less than full needle elongation, and shorter shoot growth. Over time the root damage leads to crown decline (sparse, tip-concentrated needles on short shoots) which limits diameter growth. Ex-pected survival once symptoms arise can range up to 15 years. This disease is typically associated with shortleaf pine (Pinus echinata). The literature does have a number of citations where loblolly pine (Pinus taeda) declines under this disease complex. Under stressful soil conditions, loblolly pine has been cited as succumbing to “spot die-out ” where a causal pathogen can not be isolated but the symptoms are similar to littleleaf disease. Because of loblolly pine’s importance as a commercial timber species and its role as a landscape shade tree, this literature review was prepared to help the resource manager and plant health care specialist