Awards issued prior to january 20, 2025, were funded under previous administrations and may not reflect the priorities and policies of the current administration.** crapemyrtle (lagerstroemia SP.)…

Awards issued prior to january 20, 2025, were funded under previous administrations and may not reflect the priorities and policies of the current administration.** crapemyrtle (lagerstroemia SP.) is one of the top-selling deciduous flowering shrubs and are dominant landscape plants throughout the southern united states (chappell ET AL. 2012). Crapemyrtles are used in landscaping and environmental development by public planners, private businesses, and homeowners alike. According to the united states department of agriculture, the national agricultural statistics service census of horticultural specialties found that annual crapemyrtle sales were $69 million in 2019. This makes crapemyrtle a lucrative crop with high aesthetic value throughout the region. Many factors influence the profitability of the crapemyrtle industry, including consumer demand for color, the costs of production, and pest management expenditures.crapemyrtles are threatened by several key insect pests. Crapemyrtle aphid [CMA, tinocallis kahawaluokalani kirkaldy (hemiptera: aphididae)] is one of the economically significant pests that negatively impacts the appearance and growth performance of crapemyrtle (herbert and mizell III 2006, frank 2019). Foliar feeding by aphids stunts growth and distorts leaves. The aphids also reduce theaesthetic quality of plants by secreting honeydew, which results in outbreaks of sooty mold on foliage. Foliar feeding beetles, including japanese beetle (popillia japonica newman) and flea beetles (altica SPP.), can reduce growth and aesthetic value of plants in production and landscape. In 2004, a new insect pest of crapemyrtle was found infesting plantings in richardson, texas. Like the crapemyrtle aphid, crapemyrtle bark scale [cmbs; acanthococcus lagerstroemiae kuwana], feeds on the plant vascular tissue, but does so through the bark instead of the foliage (chappell ET AL. 2012, frank 2019). Heavy infestations result in leaf abscission and branch dieback. Cmbs also produces copious amounts of honeydew, which results in unsightly sooty mold on the foliage and areas surrounding the plant.crapemyrtles can also be negatively impacted by diseases. Powdery mildew (PM), caused by the fungus erysiphe lagerstroemiae, is the most widespread and damaging disease observed in crapemyrtle. IT occurs most often on young, actively growing plant tissues, reducing growth. Another common disease of crapemyrtle is cercospora leaf spot (CLS), caused by the fungus pseudocercospora lythracearum heald and wolf. Resistance to both pathogens has been evaluated in many of the older crapemyrtle cultivars, with the identification of PM resistance being historically important to plant breeding programs.currently, in tennessee, the most important insect pest of crapemyrtle is the aphid. Previous studies on the susceptibility of crapemyrtles to CMA attack have indicated that plant parentage (l. Indica versus l. Indica × l. Fauriei) and mature plant height (dwarf, medium, or tall) can predict CMA resistance (alverson and allen 1992, mizell and knox 1993, pettis ET AL. 2004). Greater CMA populations have been observed on l. Indica &TI, MES; l. Faurei cultivars than on cultivars of the species l. Indica (herbert ET AL. 2009, mizell III & knox 1993), indicating that susceptibility to CMA may be pleiotropic (ribeiro ET AL. 2021). Dwarf plants were more resistant to CMA than medium or tall plants (herbert ET AL. 2009, mizell III & knox 1993). Crapemyrtle bark scale arrived in tennessee in 2013 in memphis and has been slowly moving east into major cities. IT is not yet present in the nursery production region of middle tennessee. To date, resistance to cmbs has not been reported in any commercially available cultivar of crapemyrtle in the USA. Only the tropic species l. Speciosa has shown any resistance to cmbs in trials (WU ET AL. 2021).the main pathogen of concern to crapemyrtle in tennessee is powdery mildew. Incorporating powdery mildew resistance into crapemyrtle has been a focus of breeders for decades. Cultivars with pure l. Indica genetics tend to be more susceptible to powdery mildew. The US national arboretum pioneered the release of l. Indica × l. Fauriei hybrids with powdery mildew resistance. Most popular cultivars currently on the market have some level of powdery mildew resistance (chappell ET AL. 2012). However, as mentioned previously, resistance to powdery mildew may come at the cost of aphid susceptibility, and vice versa.on the production side, this research proposal will focus on the relationship between how resistance to CMA and powdery mildew is expressed under two different growing conditions: greenhouse (controlled environment) and field container production (open-air). We will also consider how management recommendations may change based on production stage (propagation or finishing) and management options (conventional chemicals or biological controls). While host plant resistance can be a great tool for pest management, there may be negative effects as well. For example, plants with some level of resistance to aphids due to higher levels of toxic compounds mayinadvertently result in negative fitness costs on natural enemies that consume them. These multi-trophic interactions will be explored further in this grant.