Prevent Garden Pests by Rotating Crops

February 23rd, 2009 by david laferney Leave a reply »

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Before farmers had the option of battling pests and diseases by applying petroleum based poisons to crops or tampering with genetic designs they worked out sustainable systems to manage  insects and pathogens by rotating crops.

The concept of crop rotation is simple – don’t plant the same thing in the same place year after year.  Most crop rotation plans  call for you to plant a crop in the same  place only every three or more years, and include a fallow year in the schedule.  Fallow means that no cultivation takes place during that period, although the land was often used to pasture livestock during the fallow year.

Crop rotation prevents the build up of disease and pests by denying species specific  organisms the hosts that they need to live and reproduce over multiple years.  It makes sense that during a year of cultivating potatoes, that potato problems – potato beetles, and late blight for example – would leave their eggs and spores in the soil, just waiting for you to plant potatoes next year.  You can imagine what an unsustainable problem this can result in if you farm hundreds of acres of potatoes on the same land year after year.

Fortunately the home gardener is usually growing a variety of crops instead of the same one over and over and isn’t at the mercy of the commodities market when deciding what to plant where. If you are an organic gardener then crop rotation along with feeding the soil, companion planting, and other sustainable methods can allow you to maintain a balance between the beneficial and non-beneficial organisms  in your garden so that losses are kept to a reasonable level.

Simple Crop Rotation

Simple Crop Rotation

Crop rotation also helps to manage soil fertility – legumes add nitrogen to the soil, heavy feeders like tomatoes use lots of nitrogen – so you see that your plants can actually help to feed each other.

So – Don’t plant the tomatoes in the same place as last year – Simple.  Right?  Not quite that simple actually.  The thing is that tomatoes, potatoes, tobacco, peppers, and eggplants are in the same plant family, and should be treated as one thing when planning your crop rotation. So, don’t plant any of those in the same place that any of the others occupied previously in the rotation schedule.  This takes some planning to pull off effectively. If you haven’t already, you should start a garden record – go ahead and write down whatever you can recall from years past.

A list of some common garden plant relationships:

  • Leguminosae: Legumes – bean, pea, peanut, clover
  • Solanaceae: tomato, eggplant, pepper, potato, husk tomato, tobacco
  • Brassiceae: cabbage, broccoli, cauliflower, kale, broccoli raab, pak choi, mustard, kohlrabi, Brussels sprout, turnip, radish, rutabaga, collard
  • Cucurbitaceae: Cucurbits – cucumber, squash, pumpkin, melon, watermelon, gourd
  • Umbelliferae: carrot, parsley, celery, parsnip, dill, fennel, coriander, Queen Anne’s lace
  • Liliaceae: Lilly – asparagus, garlic, onion, leek, shallot, chives, ornamental lillies
  • Chenopodiaceae: beet, Swiss chard, spinach, lamb’s quarter, amaranth, purslane
  • Asteraceae: chicory, endive, salsify, dandelion, lettuce, sunflower, marigold, Jerusalem and globe artichoke.

Being aware of these relationships will help you to work out a system of management that works for you in your garden.  A 3 (or 7) year rotation that includes a fallow year may or may not be doable for you, but if you do the best that you can with the resources that you have you should be able to produce more without having to spray poison on your families food.

Recommended additional reading:

Edible Landscaping with Charlie Nardozzi :: National Gardening Association.

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