University of Maryland Extension

Wilt, Fall Over, or Cut Off at Soil Line - Vegetable Seedlings and Transplants

Back to Common Problems - Vegetables

- Cutworms

- Damping-off disease

A number of soil-borne, fungal and bacterial root rots affect a wide range of vegetable crops. Three fungal diseases, Phytophthora, Pythium, and Rhizoctonia, are collectively referred to as "damping off". These pathogens are water molds- they must have free water to grow and reproduce. Damping-off can affect seeds in the ground prior to germination as well as young seedlings. Seedlings grown inside homes under fluorescent lights and in greenhouses succumb to damping-off if the media is poorly drained and kept too wet. In the garden, the disease can be a problem on poorly drained soils during cool, wet, and cloudy spring weather. Symptoms are more likely to be observed on slow-growing, weak plants. Above ground symptoms include leaf yellowing and browning, stem cankers, and stunted and wilted plants.

Rhizoctonia girdles or constricts lower stems (this is known as "wirestem") and pythium causes stunting, browning and malformation of the root system. Damping-off is more likely to infect large seeds (corn, bean, pea).

Management:

Transplants and seedlings:

Use soilless potting media for growing transplants. Don't over-water seedlings grown indoors or in a greenhouse or cold frame. Allow the top of the growing mix to dry slightly before watering. Plant seeds and transplants in loose, well-drained soil. Infected plants should be pulled up immediately, indoors or out in the garden, and composted.

In the garden:

Avoid planting seeds or transplants in low-lying, poorly drained areas. Plant on raised beds if your garden soil stays wet for days following rainfall. Plant at the proper depth and spacing. If you've had a problem with damping-off, dig in lots of mature compost but avoid incorporating un-decomposed organic materials prior to planting (straw, leaves, fresh manure, etc.).

Seeds can also be pre-sprouted to give them a head start. Place seeds on a moistened paper towel. Roll up the paper towel, place it in a plastic bag with some holes and set it on top of the refrigerator. Check the germination rate after 5-7 days. When the radicle (new root) begins to develop, remove seeds and plant in garden soil. However, do not pre-soak bean and corn seeds in water. This treatment will make them more susceptible to soil pathogens.

Infected plants should be pulled up immediately, indoors or out in the garden, and composted.

- Environmental Stress

Drought, sustained winds, water-logged soil, poor quality transplants, temperature extremes, and cloddy or compacted soils high in clay can all cause the stunting of young seedlings or transplants. Providing optimum conditions for good growth at this early stage will help ensure healthy growth and good yields through the season. Follow these cultural recommendations:

  • Plant in well-drained soil high in organic matter.
  • Use high-quality seed and transplants. Check transplants prior to purchase. Avoid plants with roots that are brown and growing around the bottom of the container.
  • Keep soil evenly moist and fertilize with a balanced soluble fertilizer after seedlings emerge or after transplanting.
  • Protect plants from wind and cold with floating row cover material, cold frame, or cloche (e.g. an empty 1 gallon plastic milk jug with the bottom removed).
  • Avoid damaging plant roots through cultivation, tilling or walking on the soil.

Plants grown under poor conditions will not produce adequate foliage or yields. In addition, low yields and poor eating quality can be expected if plant growth is checked significantly at any point in the life cycle- from seedling to fruit maturation.

- Seedcorn maggot

- Slugs

- Southern corn rootworm

This is the larva of the spotted cucumber beetle. It has a white to cream colored body with a brown head and reaches ½ inch in length. Larvae tunnel into the roots and stems of corn, bean, and cucurbit seedlings. Exclude this pest with a floating row cover or plant extra seed to allow for some injury. Seeds can also be pre-sprouted to give them a head start. Place seeds on a moistened paper towel. Roll up the paper towel, place it in a plastic bag with some holes and set it on top of the refrigerator. Check the germination rate after 5-7 days. When the radicle (new root) begins to develop, remove seeds and plant in garden soil. However, do not pre-soak bean and corn seeds in water. This treatment will make them more susceptible to soil pathogens.

Photo Gallery:

southern corn rootworm exiting stem

Southern corn rootworm

spotted cucumber beetle on leaf

Adult spotted cucumber beetle

 - Wildlife

Many wild and domesticated animals, including deer, voles, rabbits, birds, squirrels, groundhogs, rats, dogs, and cats may damage vegetable gardens occasionally or consistently. Be aware that wildlife tends to feed more heavily on vegetable crops during dry seasons when little water is available.

Deer, rabbits, birds, and groundhogs are the large animals most likely to feed on vegetable stems. Starlings, finches, crows, pigeons, and sparrows will dig out and consume seeds before or after they have germinated. Dogs and cats may also trample young seedlings.

Animal tracks, droppings, the height of the cut off stems, and type of chewing injury can provide clues that aid in identification of the culprit(s). In un-fenced gardens, more than one type of animal may be feeding on plants. Deer may feed on almost any type of vegetable plant, depending on available foods, numbers of deer, time of season, garden location, etc. Groundhogs are also fond on many different vegetable plants but seem to prefer members of the cabbage and cucumber families and sweet potato foliage (they generally do not eat eggplant or pepper foliage). Rabbits are more found of crucifers, leafy green vegetables, and beans. Deer lack upper incisors and leave a ragged edge to chewed stems. Rabbits and other rodents clip stems leaving a sharp, oblique edge. Rabbits cannot easily chew a plant stem that is more than 20 inches off the ground. Groundhogs and deer are more likely to feed in the early morning and evening. Be aware that wildlife tends to feed more heavily on vegetable crops during dry seasons when little water is available.

Below are some tips for minimizing wildlife problems:

  1. A 3 foot high fence of chicken wire or other closely woven wire is very effective at excluding rabbits, groundhogs, cats, and dogs. Be sure that the fencing extends 4-6 inches below the soil line. Groundhogs are excellent diggers.
  2. A two-strand electric fence can be very effective against a wide range of animals. The wires are strung 6-8 inches and 3 feet from the ground.
  3. Cover seedbeds and young plants with a floating row cover. This works very well for all types of wildlife.
  4. Commercial repellents are available which work well against deer, rabbits, cats, and dogs. Small deodorant soap bars hung on stakes, cages, fences, and trellises can deter deer. Deer are more readily repelled by smell than by taste. Repellents lose their effectiveness over time and after rainfall. Dried blood or crushed hot pepper can also be sprinkled around the garden.
  5. Squirrels, groundhogs, and voles can be captured in live traps and released in another location or euthanized. Check with your county wildlife control agency for details.

- Wireworms

Wireworms are slender, shiny, tough-skinned worms with pale yellow to reddish brown bodies. They can grow to over 1 inch in length. The adults are click beetles. The larvae spend 1-6 years in the soil. They feed on large vegetable seeds prior to or right after germination. They also infest young beet, sweet potato, turnip, and onion plants. Fresh holes have ragged edges and contain chewed root tissue. Wireworms can damage potato seed pieces, opening them to fungal and bacterial infections that result in weak plants.

Management: Rotate susceptible crops. Till garden soil prior to planting in spring to kill and disrupt larvae. Plan to dig and eat new potatoes rather than growing storage potatoes. To reduce wireworm populations, spear pieces of potato or carrot on a stick and bury them 2 to 4 inches deep in the garden. Dig up the pieces after a week and destroy them, along with the wireworms that are feeding inside. Set the potato traps at 3 to 10 foot intervals.

Seeds can also be pre-sprouted to give them a head start. Place seeds on a moistened paper towel. Roll up the paper towel, place it in a plastic bag with some holes and set it on top of the refrigerator. Check the germination rate after 5-7 days. When the radicle (new root) begins to develop, remove seeds and plant in garden soil. However, do not pre-soak bean and corn seeds in water. This treatment will make them more susceptible to soil pathogens.

 

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