Essay on Urban Agriculture: Safeguarding Gardens From Pathogens With Diamondback Moth Management

Most urban dwellers are engaged in urban agriculture through the creation of community gardens. Such community gardens require safeguarding from pathogens that are likely to be destructive in the production of crops. Proper management is essential in reducing and preventing pathogens that pose a threat to healthy growing plants in these farms. Concerns have emerged on best practices and management methods on controlling the feeding of diamondback moths, and thereby eliminating the spread of black rot in the gardens of Milwaukee city. It is from these concerns that this paper intends to examine suitable urban practices that would enhance urban agriculture through effective and efficient management of crop pests, notably diamondback moth infestation that causes black rot in broccoli plants.

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The practice that involves crop growing, handling, and the supply of food in urban cities is referred to as urban farming or urban agriculture (Badami & Navin, pp. 8-15). Urban gardening also consists of other farming activities such as aquaculture, urban beekeeping, animal husbandry, horticulture, and agroforestry. It enables the circulation of healthy and fresh food within an urban setting, and hence enhances food security within such a locality (Opitz et al., pp. 341-358).

Black rot is caused by a bacterium called Xanthomonas campestris pv. Campestris (Xcc). Black rot is one of the most significant diseases of cruciferous crops across the globe. An Xcc infected seed is the principal source of black rot disease. As the seed germinates, the seedling is also infected through the cotyledons and epicotyl, resulting in blackening leaf margins that wither and fall. The bacteria are hosted in the stems and leaves of the crop. At this stage, the disease reveals itself in the form of a V-shaped chlorotic to necrotic lacerations that spreads up to the foliage margins. The bacteria are dispersed by rain, wind, water drops, and mechanical means to other crops (Li et al., pp. 276-296). Diamondback moths' larvae damage crop foliage through feeding. As they feed on the underside of the leaf, they create holes in the epidermis. Instars also feed on the bottom of the foliage, cutting round holes. It is such openings that host the bacteria Xcc that causes black rot in brassica plants.

Diamondback moth referred to by the scientific name plutella xylostella has 25 to 30 days in its development from egg to the pupal stage, depending on weather conditions (Capinera, pp. 1202-1206). The eggs are always deposited on the surface of the leaf or other parts of the plant. The eggs' development time has an aggregate of about 5 to 6 days before they hatch into a larva. The larvae are always active but quite small. The larvae of a diamondback moth have four instars. The first instar feeds through the mining of the foliage before emerging, melting underneath the leaf, and continue feeding on the underside of the foliage. Pupation then takes place in a free silk cocoon on the underneath of the leaves. At about eight days, the pupa becomes a young adult, exhibiting tiny, slim, and gray color with noticeable antennae.

Control methods for controlling diamondback moth feeding to eradicate the damage they cause in plants are varied and vast. They include the use of spinetoram-based insecticides called Radiant SC, spraying with a pesticide such as biocontrol agent (Bacillus Thuringiensis), or replacing the plants with Bt-broccoli (Sharma, pp. 891-893). Pesticides are products for controlling pests on the farm, as well as weeds. Synthetic pesticides are generated through chemical reactions, while natural pesticides are products created from natural sources with little or no chemical transformation. Registered or certified organic pesticides are manufactured through strict standards that conserve natural resources and the environment. Pesticides that contain elements such as heavy metals, sulfur, and salt compounds are referred to as elemental pesticides. The earliest elemental pesticide contained sulfur and was used in various control methods.

Radiant SC insecticide controls several stages of diamondback moth growth and offers residual control. The poison maintains the population of the moth through a defined integrated pest control style. Radiant SC insecticide is best applied in rotation with other pesticides to ensure that the pests do not develop resistance.

Bacillus thuringiensis (Bt) is a naturally occurring microbe found in soils. The bacterium produces proteins that are toxic to young larvae. When the larvae feed on foliage containing the bacillus thuringiensis (Bt), the toxins are activated within their guts. The activated toxins kill the insect through starvation and infection. Bt-insecticide can be sprayed, dusted, or administered in the form of pellets. The pesticide is effective; it kills pests within hours and has no known side effects to beneficial pests and humans (Keshavareddy & Kumar, pp. 3035-3051). Replacing the plants with Bt-broccoli is also another pest control method. However, there are rare species in B. oleracea that are resistant to Xcc, making the success of such an approach to be limited. The above methods have efficacy; they are environmentally friendly and have the potential of increasing food productivity.

Other management methods that can be deployed include the removal of debris after harvest, crop rotation, observing hygiene and sanitation, and controlling cruciferous weeds that may harbor pathogens.

Works Cited

Badami, Madhav G., and Navin Ramankutty. "Urban agriculture and food security: A critique based on an assessment of urban land constraints." Global Food Security 4 (2015): 8-15.

Capinera, John L. "Diamondback Moth, Plutella xylostella (Linnaeus Lepidoptera: Plutellidae)." Encyclopedia of Entomology (2008): 1202-1206.

Keshavareddy, G., and A. R. V. Kumar. "Characterization of Bt Transgenic Plants: A Review." Int. J. Curr. Microbiol. Appl. Sci 7 (2018): 3035-3051.

Li, Zhenyu, et al. "Biology, ecology, and management of the diamondback moth in China." Annual review of entomology 61 (2016): 277-296.

Opitz, Ina, et al. "Contributing to food security in urban areas: Differences between urban agriculture and peri-urban agriculture in the Global North." Agriculture and Human Values 33.2 (2016): 341-358.

Sharma, Purushotam, et al. "Bioefficacy of different insecticides against diamondback moth." IJCS 5.3 (2017): 891-893.