Effect of Different Rates, Application Timing, and Combination of Nonfumigant Nematicides in Control of Meloidogyne incognita in Watermelon

Abstract

The use of plasticulture systems, which consist of raised beds, plastic mulch, and drip irrigation for watermelon production, has increased in the Southern United States in recent decades. The root-knot nematode (RKN), Meloidogyne incognita, is a significant pathogen of watermelon production in plasticulture systems and can cause varying levels of yield loss depending on the nematode population density if not properly controlled. Few new non-fumigant nematicides (fluensulfone, fluazaindolizine, and fluopyram) have emerged in the last decade to help manage RKNs. A two-year field study was conducted to examine the impact of different rates, application timing (i.e., days before transplanting [DBT], at transplanting [AT], and days after transplanting [DAT]), and combination of these new nematicides and an older one (oxamyl) in control of RKN in watermelon cv. ‘Fascination’. The nematicide treatments, except for a single-time application of oxamyl in 2019 and 2020, significantly reduced root galling compared to the untreated check. Similarly, all treatments, except a single application of oxamyl in 2020, resulted in a lower soil population level of M. incognita than the untreated check. All nematicide treatments, except a single application of fluensulfone and a two-time application of fluopyram at a half-recommended rate, increased fruit yields when compared to the untreated check. Overall, the drip application of new chemistries, known as 3-F nematicides, shows to be a useful option for RKN management in watermelon. At planting application of fluazaindolizine or fluopyram and two-time applications of oxamyl based on the manufacturer's recommended rate show potential to prevent the crop loss.

Upgrading Strategies for Managing Nematode Pests on Profitable Crops

“…Emerging/novel tactics and strategies can use a variety of improved materials and techniques that encompass novel chemical nematicides [ 47 , 48 , 49 , 50 ], more PPN-resistant genotypes [ 32 ], additional certified seed/planting material [ 51 ], more timely and optimized soil solarization for PPN disinfestation [ 52 ], and novel bionematicides [ 53 ] along with one or more production practices related directly/indirectly to PPN control. These production practices may include ploughing, crop sequencing, fallowing, cover crops, flooding, and/or soil amendments.…”

“…Fluopyram demonstrated a high nematicidal efficacy against several serious PPN genera, such as root-lesion nematodes, RKNs, cyst nematodes, and potato rot nematodes. Furthermore, in a 2-year field study to control Meloidogyne incognita infecting watermelon, Nnamdi and Hajihassani [ 49 ] tried to further optimize the efficacy of three novel nematicides (fluensulfone, fluazaindolizine, and fluopyram), known as 3-F nematicides. They applied them at different times (days before transplanting, at transplanting, and days after transplanting), nematicidal rates, and combinations (including with an old one, oxamyl).…”

“…Similarly, except for a single use of oxamyl in the year 2020, all treatments manifested a lower M. incognita population level in soil than the untreated control. Overall, they [ 49 ] concluded that drip application of the novel 3-F nematicides demonstrated a profitable option for managing M . incognita on watermelon.…”

“…Meanwhile, exploring the spatial distribution of nematode pests in the field will improve sound management decisions [ 102 ] and lead to exact practicability of site-specific nematicide application to lower the required dosage [ 28 ]. In other words, it is still quite possible to include chemical nematicides as components within the INM given the aforementioned tactics [ 49 , 52 , 68 ] and precautions [ 103 ]. Such precautions of fumigants in novel PPN control strategies impose restrictions in terms of enlarged buffer areas, localized decreases of VOCs being freed into the atmosphere, and proper personal equipment to protect field workers [ 103 ].…”