Shah Alam of Hodson Lab to Present Exit Seminar on Sept. 4
'Management Strategies and Disease Interactions of Resistance Breaking Root-Knot Nematodes'
Master's degree candidate Shah Alam of the Amanda Hodson lab, UC Davis Department of Entomology and Nematology, will present his exit seminar on "Management Strategies and Disease Interactions of Resistance Breaking Root-Knot Nematodes" at 1 p.m., Friday, Sept. 4 in Room 176 of Hutchinson Hall.
Alam, to receive his degree in September, holds a bachelor's degree in agriculture, Patuakhali Science and Technology University, Bangladesh (2017).
His abstract: "Processing tomatoes are economically important to California, as the state accounts for approximately 95 percent of total U.S. production; root-knot nematodes in the genus Meloidogyne are considered highly damaging to this crop. Commercial tomato cultivars containing the Mi gene have been considered an effective option for managing root-knot nematodes. However, resistance-breaking root knot nematode populations have been identified in recent decades, posing a significant threat to the processing tomato industry.
"To determine if cultivars vary in quantitative resistance traits, in Chapter 1, I assessed the relative susceptibility of five tomato cultivars to four resistance breaking root knot nematode isolates—two each of Meloidogyne incognita (#157 and #213) and M. javanica (MJ198 and MJJDC). Results suggest that none of the tested cultivars differ in quantitative resistance levels, but there are differences in reproduction between nematode isolates, so that the aggressiveness of isolates may play a more important role than the cultivars grown in a particular field."
"Root-knot nematodes (RKN) and Fusarium wilt are both detrimental to tomato health in California. Individually, each pathogen poses a significant threat to processing tomato production; however, when they occur together, they may form a disease complex which increases disease severity and subsequent yield loss. A greenhouse experiment (Chapter 2) was conducted to determine whether prior RKN inoculation with the resistance breaking Meloidogyne incognita isolate, VW5: 1) increased the severity of Fusarium oxysporum f. sp. lycopersici race 3 (Fol R3) symptoms, 2) predisposed resistant plants to breakdown of Fol R3 resistance, or 3) affected plant biomass. Two tomato cultivars were tested, a Fol R3 susceptible F2 processing tomato cultivar and an Fol R3 resistant F3 cultivar. Combined infection with VW5 and Fol R3 increased chlorosis compared with either pathogen alone in the F3 cultivar, whereas combined infection increased chlorosis only compared with Fol R3 alone in the F2 cultivar. In the F3 tomato cultivar, severe decline was also greater in the combined treatment during the early stage of disease development than with either pathogen alone. These findings indicate that RKN infection may enhance the progression of Fusarium wilt symptoms and negatively affect plant growth. Therefore, management strategies targeting both pathogens simultaneously may be more effective for processing tomato production than managing either pathogen independently."
Disease complexes involving root knot nematodes (RKN) and Fusarium stem rot and vine decline (FRD) (caused by F. noneumartii and F. martii) commonly co-occur in California tomato production. However, few studies have evaluated the efficacy of non-fumigant alternatives against both RKN and FRD (or any other) fungal pathogens simultaneously. In Chapter 3, two field trials were conducted to evaluate non-fumigant nematicides for co-managing RKN and FRD. The first trial, conducted in the processing tomato cultivar ‘HM 8237,’ evaluated the product Salibro. The second trial, conducted in fresh-market tomato with the cultivar ‘Temecula, FM- F2' evaluated four chemical nematicide treatments (Nimitz, Salibro, Velum One, Velum One plus Zironar) and one biological treatment (Zironar alone). In the processing-tomato trial, Salibro did not significantly affect plant-parasitic nematode abundance, root galling, stem rot, or mild and severe vine-decline symptoms compared with the untreated control. Nevertheless, Salibro-treated plots produced significantly greater yield. In the fresh-market tomato trial, Nimitz, Salibro, Velum One, Velum One plus Zironar, and Zironar did not significantly affect nematode abundance or root galling relative to the non-treated control. Similarly, none of the treatments significantly reduced Fusarium stem rot, vine decline, or internal rot severity. However, Velum One significantly increased total fruit biomass relative to the non-treated control. The finding that Salibro increased yield in processing tomato, whereas Velum One increased yield in fresh-market tomato, suggests that these non-fumigant nematicides may improve tomato productivity in fields co-infested with RKN and FRD despite having limited measurable effects on nematode populations and disease symptoms, which were more variable within plots."
Alam, a graduate student researcher at UC Davis since 2023, has collaborated with UC Agriculture and Natural Resources (UC ANR) farm advisors, university faculty, growers, Pest Control Advisors, and industry partners to design and implement greenhouse and field experiments.
He previously worked as a research assistant at Clemson University (2021-23).
His career plans? "I hope to serve the agricultural community through a government position."