University of Maryland Extension

Pest management: weeds, diseases, insects, and more!

Author: 
Neith Little, Extension Agent, Urban Agriculture


Urban Ag home | Table of contents

 The holes in this eggplant are an example of the kind of cosmetic damage that insect feeding can cause. Photo by Neith Little.
Figure 17: The holes in this eggplant are an example of the kind of cosmetic damage that insect feeding can cause. Photo by Neith Little.

 

Pests can quickly eat up an urban farmers’ yields and profits—quite literally!

How to prevent and control pests is a huge topic; much bigger than can be satisfactorily covered here. This section will introduce the “big three” types of pests, basic elements of a pest management strategy, brief thoughts on how these pests and strategies apply to urban farming, and links to references where you can learn more.

The big three: Some people think of pests as specifically animals: insects, other invertebrates, and vertebrate critters like rodents, deer, and birds. Other times people will include weeds and diseases within the definition of “pests.” All these kinds of pests can reduce crop yield, harm livestock, and cause cosmetic damage that makes fruit and vegetables undesirable to customers (Figure 18).

  • Weeds are plants that compete with your crops for space, light, and nutrients. If you raise livestock, weeds might be a feed source, or certain poisonous weeds might be a risk to your animals. To help you identify weeds on your farm, I recommend either Weeds of the Northeast, by Uva, Neal, and DiTomaso or Weeds of the South by Bryson and DeFelice.

    Plant identification smartphone apps are also available, as well as an excellent Facebook group: https://www.facebook.com/groups/156706504394635/

     Bird netting held up by small poles and staked down around the edges can protect small seedlings from being uprooted by squirrels. Photo by Neith Little.
    Figure 18: Bird netting held up by small poles and staked down around the edges can protect small seedlings from being uprooted by squirrels. Photo by Neith Little.

  • Different diseases affect plants and animals. If you are growing crops in Maryland, University of Maryland’s Plant Diagnostic Lab is an amazing resource for help diagnosing plant diseases: https://extension.umd.edu/plantdiagnosticlab.

    If you are raising livestock, the best resource on animal diseases is a veterinarian who is used to working with agricultural animals. If you are raising chickens and other poultry, UMD’s small flock production website has some great introductory articles and videos on preventing and monitoring for poultry diseases: https://go.umd.edu/smallflock
       
  • Invertebrate and vertebrate pests feed on crops and livestock and spread diseases. Invertebrate pests include things like slugs, nematodes, and mites, as well as true insects like thrips, aphids, grasshoppers, beetles, and caterpillars. On outdoor urban farms in Baltimore, particularly troublesome invertebrate pests include flea beetles (multiple species), squash bugs (Anasa tristis), harlequin bugs (Murgantia histrionica), the caterpillars of cabbage moths (Mamestra brassicae), and spotted and striped cucumber beetles (multiple species, can transmit squash wilt disease). In high tunnels and indoor production, aphids, thrips, whiteflies, and spider mites can quickly build up to high populations. When it comes to vertebrate pests on urban farms,everyone asks about rats. But anecdotally, what urban farmers have told me is that rats prefer to eat trash rather than vegetables. Rats may feed on fruit crops, particularly melons. In general though, I have found squirrels to be a bigger problem than rats for urban production, not because squirrels eat that much produce but because they appear to obsessively dig up any loose soil, killing small seedlings. An urban farmer named Clayton Williams taught me to use bird netting to exclude squirrels, and I have found that to work well (Figure 19). Mulch can also help deter squirrel digging behavior.

    • Deer, gophers, and groundhogs are also important vertebrate pests of urban farms. Excluding deer can be difficult and expensive, especially once they know something delicious is growing on your site. Jonathan Kays of UMD Extension has a comprehensive guide to deer exclusion options: https://go.umd.edu/deerexclusion 

    • When it comes to livestock, invertebrate parasites are the main concern. Sheep and goats, for example, are plagued by parasites. For more information, see UMD’s small ruminant website: https://www.sheepandgoat.com/
        
    • Fish and other aquaculture “livestock” can also be infected by various diseases and parasites. UMD Extension has a helpful factsheet on aquaculture biosecurity here: https://go.umd.edu/aquaculturebiosecurity   

 

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