Evaluation of Post Emergence Applications of Mustard Seed Meal for Weed Control in Chile Pepper

Asmita Nagila1*, Brian Schutte1, Soum Sanogo1 and John Idowu2 New Mexico State University 1Department of Entomology, Plant Pathology and Weed Science; 2Extension Plant Sciences *[email protected] INTRODUCTION • Pre-plant applications of MSM suppress weeds and soil-borne pathogens [1]; however, MSM applications after crop emergence(i.e.,”POST applications”) are poorly understood. • POST applications of MSM potentially injure crops because of MSM’s pesticidal property is due to volatile compounds (e.g., isothiocyanates) released after hydrolysis of glucosinolates [2]. • Chile pepper is a slow growing crop that competes poorly against weeds and is susceptible to soil-borne pathogens [3]. • Chile pepper weed control programs might benefit from POST applications of MSM, provided that such applications suppress weeds without injuring the crop. (A) Mustard seed meal application B) Study sites

OBJECTIVES RESULTS: Greenhouse study RESULTS: Field study 1.Conduct a greenhouse to identify MSM application method • Surface applications at the high rate inhibited chile pepper photosynthesis • MSM at the high rate reduced weed and Palmer amaranth emergence; and rate that is safe for emerged chile plants. throughout the study period. however, weed and Palmer amaranth emergence was not suppressed by 2.Using insights from Objective 1, determine if the method control • By six days after application, MSM no longer inhibited photosynthesis in MSM at the low rate (Table 1). weeds and maintain fruir yield for chile pepper grown in field.… surface applications at the low rate. • Chile pepper fruit yields were similar between MSM-treated plots and control plots. • Buried applications at the high rate initially reduced photosynthetic rates; MATERIALS AND METHODS but, by eight days after application, photosynthetic rates were comparable • MSM – Brassica juncea to the control treatment. Control Table 1: Parameter estimates from negative binomial generalized linear • Glucosinolate (sinigrin) concentration: 203 μmol/g quantified by Low rate, buried Low rate, surface mixed models of mustard seed meal (MSM) effects on weed seedling Adam-Dohney’s Method [4] High rate, buried High rate, surface emergence, Palmer amaranth seedling emergence and guassian mixed 25 a model on chile pepper fruit yield.( within coloumn ,same alphabet represents Greenhouse study a a a a Treatment and Design ) a a a a no significant difference).

-1 a 20 a a a • Randomized complete block design with 4 replications s a a -2 a a a a a • Experimental unit : three chile pepper plants grown in soil for 8 m b MSM Rate Parameter Weed Palmer Chile pepper 2 15 b weeks before MSM application.(figure 1) b seedling/0.25 seeedlings/ fruit yield(kg/4m) • MSM treatments: Factorial combination of MSM rate (4400kg/ha, b m2 core 10 b

2200kg/ha) and application location (Surface, Buried) CO mol High Intercept (control) 7.8a 9.1a 6.79a u b c

( b b Data Collection rate Photosynthetic b 5 c • Photosynthestic rate measured using LIcor- 6400 every 2 d b MSM treated 1.4b 1.0b 7.20a c b after MSM application (figure 2). c 0 Low Intercept (control) 5.6a 7.7a 5.12a • Height, fresh weight, dry weight, and leaf area at 14 days after 0 2 4 6 8 10 12 14 MSM application Day after application MSM treated 2.8a 4.5a 5.13a Data Analysis Figure 3:Photosynthetic rate of chile pepper leaves from Day 0 to day 14 of MSM application.(same alphabet • ANOVA and Post hoc Tukey test from R software within a day representing no significant difference)

• Chile pepper height, biomass and leaf area were similar between the DISCUSSION AND CONCLUSIONS control and buried application treatments (Figure 4).Surface applications at • Weed control requires MSM applied at a high rate; but, emerged chile the high rate resulted in chile pepper plants that were smaller than control pepper plants are susceptible to injury from high amounts of MSM on the treatment. Surface application was dropped from treatments in field study soil surface. after the result in greenhouse. 500 Figure1 Figure 2 25 • Burying MSM protects chile pepper plants from damage that would occur a a a a if MSM was on the soil surface. 400 Field Study a 20 a

Locations, treatment and design 2) ab • MSM applied at the high rate and incorporated in soil can be used to 300 •Two university research farms and two commercial farms. 15 a control late-season weeds in chile pepper. Such weeds reduce chile yield and hinder chile harvest. 200 •Experimental unit: row of 6m ( paired, untreated control plot ) 10 •For each MSM rate (4400 kg/ha, 2200 kg/ha) within a site, (cm area Leaf 100 b randomized complete block design with 4 replications 5 b LITERATURE CITED •MSM applied and incorporated in furrows between neighboring weight(g) aboveground Fresh 0 0 [1] Boydston, R., McGuire, A., Vaughn, S., & Collins, H. (2007). Effect of mustard seed meal on early weed

rows. Control emergence in peppermint and potato. Pacific Northwest, 5(2), 4-6. LowBuriedLowsurfaceHighBuriedHighsurface Control [2] Rask, L., Andréasson, E., Ekbom, B., Eriksson, S., Pontoppidan, B., & Meijer, J. (2000). Myrosinase: LowBuriedLowsurfaceHighBuriedHighsurface gene family evolution and herbivore defense in Brassicaceae. Plant Molecular Biology, 42(1), 93-114. 5 [3] Schroeder,J(1993). Late-Season Interference of Spurred Anoda in Chile Peppers .Weed Science, Vol. 41, Data collection 18 a a No. 2 (Apr. - Jun., 1993), pp. 172-179 •Weed emergence determined every 7 d for 28 d after MSM 16 a 4 a a [4]Doheny-Adams, T., Redeker, K., Kittipol, V., Bancroft, I., & Hartley, S. E. (2017). Development of an application: a 14 efficient glucosinolate extraction method. Plant Methods, 13(1), 17. 1.Palmer amaranth (Amaranthus palmeri) in seeded cores 3 12 ab 10 (6-cm diameter PVC pipes) b Acknowledgements 2 8 We are thankful for field and laboratory assignment of Ed Morris, Joshua Bleiweiss, Andres Indacochea,

2 b Height(cm) 2.Ambient weeds in permanent, 0.25푚 quadrats biomass(g) Dry 6 Israel Marquez, Joseph Wood, Prashasti Agarwal and Abdur Rashid. • Chile pepper fruit yield 1 4 c 2 We are grateful to our chile pepper growers who collaborated and cooperated with us for conducting Data Analysis research in their field. 0 •Weed emergence data: Negative binomial mixed models 0 Control Control This project is supported by the Sustainable Agriculture Research and Education (SARE) program with LowBuriedLowsurfaceHighBuriedHighsurface •Yield data: Gaussian mixed model in R software. LowBuriedLowSurfaceHighBuriedHighSurface funding from National Institute of Food and Agriculture, USDA. SARE Project SW18-059 Figure 4: Dry Biomass, fresh weight,Leaf area and height of chile pepper plant through destructive sampling.(same alphabet represent no significant difference)