Hydrogen Peroxide for Insect and Algae Control in a Lettuce Hydroponic Environment

Abstract

Insects and algae demonstrate adaptability in hydroponic environments. Algae attract flies, Bradysia spp. (Diptera: Sciaridae) and Scatella stagnalis (Diptera: Ephydridae), called fungus gnats and shore fly, respectively. Flies feed on algae, damaging seedlings radicellae, and may transmit pathogens to lettuce plants. Little information on the management of flies and algae is known. A paradox in the face of the expansion of hydroponics. The objective was to evaluate the potential of hydrogen peroxide (H 2 O 2 ) as an insecticide and algaecide agent. Entomopathogenic fungi were also evaluated as an alternative control to flies. The experiment was conducted in a commercial hydroponic system under a randomized complete block design with 5 treatments and 4 replicates. The treatments, sprayed on the phenolic foam plates, immediately after lettuce seed deposition, were: H 2 O 2 , Beauveria bassiana, Metarhizium anisopliae, Spinosyn and water, as control. The quality of the lettuce seedlings (cv. Brida), the presence of flies and algae evolution in the phenolic foam plates were recorded daily. H 2 O 2 and Spinosyn affected lettuce seed germination, but were able to reduce adult flies on the phenolic foam cells. The highest number of larvae was observed with both fungi, and only water, compared to H 2 O 2 . No larvae were found in Spinosyn sprayed phenolic foam cells. However, lettuce seedlings from Spinosyn sprayed plates were those with lower fresh weight. H 2 O 2 severely retained algae infestation in phenolic foam cells over a 15-day observation period. The present work demonstrates the potential that H 2 O 2 can play as an insecticidal and algaecide agent in hydroponic environments.

Timing and Rates of Two Products Using Hydrogen Peroxide (H2O2) to Control Algae in Ebb and Flow Hydroponic Systems

“…It is a common practice in hydroponics to clean the system manually by basic cleaning or using black plastic sheets to reduce algal growth (V€ anninen and Koskula, 1998), but time for application and high use of labor adds to costs (Caixeta et al, 2018). Alternatively, chemical algaecides are also used occasionally (Nonomura et al, 2001).…”

“…Although H 2 O 2 -based products have been used widely as aquatic herbicide and algaecide in wastewater treatment, its application in hydroponic crop production is still limited (Caixeta et al, 2018). The signaling role of H 2 O 2 in plants is well established, particularly with reference to plant processes like stress acclimation, cell wall cross-linking, stomatal behavior, phytoalexin production, regulation of the cell cycle, and photosynthesis.…”

Effects of Hydrogen Peroxide Products on Basil, Lettuce, and Algae in an Ebb and Flow Hydroponic System

“…Hydrogen peroxide is often one of the more popular choices, especially early in the process of investigating the best chemical means to prevent algae [11,12]. Known for its abilities as a sterilizing agent, hydrogen peroxide has been shown to prevent or contain algal growth in various hydroponic environments [13,14]. Hydrogen peroxide has been shown to cause limited degradation of intracellular materials when used alone, as well as having oxidative properties.…”

“…Hydrogen peroxide has been shown to cause limited degradation of intracellular materials when used alone, as well as having oxidative properties. This allows hydrogen peroxide to be useful in curbing algal growth while maintaining a low phytotoxic effect on the crops within the system [13][14][15]. There is a slight downside to hydrogen peroxide, which is high phytotoxicity in seedlings.…”

“…As an algicide, hydrogen peroxide can decrease metabolic processes, destroy pigment synthesis and membrane integrity, inhibit photosynthetic activity and genes expression, alter circadian rhythms, and induce apoptotic-like cell death while limiting growth; however, the efficacy of hydrogen peroxide is dependent on culture density, and how protected the pigments are inside of the chloroplasts [11,23,24]. While hydrogen peroxide is often combined with UV in irrigation lines to prevent algae build up, the chemical can also cause phytotoxic effects in seedlings [13,14,25,26]. While hardier seedlings often can recover, more delicate seedlings, such as lettuce (Lactuca sativa L.), are more prone to have a lower fresh weight and biomass than seedlings that were not treated with hydrogen peroxide [13].…”