While common garden pests like aphids, slugs, and tomato hornworms often steal the spotlight, there is a host of lesser-known garden pests and diseases that can wreak havoc on your plants. These less common intruders may not be as familiar, but their impact on plant health can be just as severe. The challenge is in identifying these hidden threats and managing them before they cause significant damage.

In this blog post, we’ll explore some of the lesser-known garden pests and diseases, how to identify them, and effective strategies to manage them. By expanding your pest and disease knowledge, you can ensure your garden remains healthy and resilient, no matter what challenges arise.

1. Root Knot Nematodes

What Are They?

Root knot nematodes are microscopic, soil-dwelling worms that invade plant roots and cause characteristic “knots” or galls to form on the roots. These pests weaken the plant by interfering with nutrient and water uptake, leading to stunted growth, yellowing leaves, and poor fruit production.

Symptoms

  • Swelling or galls on the roots.
  • Yellowing leaves or stunted plant growth.
  • Poor fruit set or distorted plants.
  • Wilting despite proper watering.

Management

  • Crop Rotation: Rotate susceptible crops (such as tomatoes, peppers, and eggplants) with nematode-resistant plants like marigolds, which can help reduce nematode populations in the soil.
  • Solarization: Use clear plastic sheets to cover the soil during hot summer months, trapping heat and killing nematodes in the top layers of soil.
  • Beneficial Nematodes: Introduce predatory nematodes (such as Steinernema species) to target and kill root knot nematodes in the soil.

2. Cucumber Beetles

What Are They?

Cucumber beetles are a group of insects that target cucurbits like cucumbers, squash, and melons. There are two common types: the striped cucumber beetle (Acalymma vittatum) and the spotted cucumber beetle (Diabrotica undecimpunctata). These beetles not only feed on the leaves and flowers of the plants but also transmit bacterial wilt and other diseases.

Symptoms

  • Small, round holes in leaves, flowers, and fruits.
  • Wilting plants due to bacterial wilt infection.
  • Yellowing or browning of plant tissues.

Management

  • Row Covers: Use floating row covers to physically prevent cucumber beetles from reaching your plants.
  • Handpicking: In smaller gardens, handpicking the beetles off plants is a simple, effective method of control.
  • Neem Oil: Apply neem oil or insecticidal soap to affected plants to deter beetles.
  • Beneficial Insects: Encourage natural predators like ladybugs and lacewings that can help control beetle larvae.

3. Fusarium Wilt

What Is It?

Fusarium wilt is a soil-borne fungal disease caused by Fusarium oxysporum, which primarily affects tomatoes, peppers, and other members of the nightshade family. The fungus invades the plant's vascular system, blocking water and nutrient flow, leading to wilting and eventual plant death.

Symptoms

  • Yellowing of leaves, often starting with the lower leaves.
  • Wilting of plants, especially during hot weather.
  • Brown or black streaks in the vascular tissue of the stem when cut open.
  • Premature plant death.

Management

  • Resistant Varieties: Use Fusarium-resistant cultivars, especially for tomatoes and peppers, to reduce the risk of infection.
  • Crop Rotation: Rotate crops every 2-3 years, avoiding planting other susceptible plants in the same area.
  • Sanitation: Clean tools, stakes, and pots between uses to prevent spreading the fungus.
  • Soil Amendments: Amend soil with organic material to improve drainage and reduce the fungal load.

4. Corn Earworm

What Are They?

Corn earworms (Helicoverpa zea) are larvae of a moth species that feed on the kernels of sweet corn, tomatoes, and other crops. The larvae burrow into the cob of corn, feeding on the kernels and leaving behind a trail of destruction. They can also damage other crops like peppers and tomatoes by feeding on the fruit.

Symptoms

  • Holes or visible tunneling in the corn kernels.
  • Evidence of larvae or frass (insect droppings) on or near the corn.
  • Deformed or damaged fruit.

Management

  • Handpicking: For small gardens, handpicking the larvae from corn cobs can be an effective control method.
  • Bt (Bacillus thuringiensis): Apply Bt, a natural bacterial insecticide, which is toxic to the corn earworm larvae but safe for beneficial insects.
  • Diatomaceous Earth: Dusting the base of corn plants with diatomaceous earth can help deter larvae from crawling up the stalk.

5. Powdery Mildew

What Is It?

Powdery mildew is a fungal disease caused by several different species, including Erysiphe and Sphaerotheca. It typically affects plants like cucumbers, squash, roses, and lilacs, thriving in warm, dry conditions. The fungus forms a white, powdery coating on the leaves, stems, and buds.

Symptoms

  • White, powdery fungal growth on the upper side of leaves.
  • Yellowing or curling of leaves.
  • Reduced plant vigor and stunted growth.
  • Premature leaf drop.

Management

  • Pruning: Remove affected leaves and stems to reduce the spread of the disease.
  • Watering Practices: Avoid overhead watering, which can spread fungal spores. Water at the base of plants early in the day to allow leaves to dry before nightfall.
  • Fungicides: Apply organic fungicides like potassium bicarbonate, sulfur, or neem oil to prevent or treat powdery mildew.
  • Resistant Varieties: Choose powdery mildew-resistant varieties of susceptible plants like cucumbers and squash.

6. Squash Vine Borer

What Are They?

Squash vine borers (Melittia cucurbitae) are the larvae of a moth that targets squash, zucchini, pumpkins, and cucumbers. The larvae tunnel into the vine, causing the plant to wilt and die. These pests can be devastating, especially during the late summer months.

Symptoms

  • Wilting or sudden collapse of squash plants.
  • Hollowed-out stems with visible entry holes.
  • Frass (insect droppings) around the base of the plant.

Management

  • Preventative Trapping: Set up pheromone traps to catch adult moths before they lay eggs on plants.
  • Row Covers: Use row covers during the early growing season to prevent adult moths from laying eggs on plants.
  • Insecticidal Soap: Apply insecticidal soap to the base of plants if larvae are detected early in the season.
  • Planting Time: Planting squash later in the season, when squash vine borer populations are lower, can reduce the risk of infestation.

7. Slime Molds (Dog Vomit Mold)

What Are They?

Slime molds, particularly the infamous “dog vomit” mold (Fuligo septica), are a type of protist that thrives in decaying organic matter. Though they are not harmful to plants, their unsightly, yellow-to-orange, slimy appearance can be alarming to gardeners. They typically appear on mulch, rotting logs, or decomposing organic material.

Symptoms

  • Bright yellow or orange, slimy masses that can grow several inches across.
  • Often found on mulch, rotting wood, or damp, shady areas of the garden.

Management

  • Manual Removal: Slime molds are harmless to plants and can be removed by simply scraping them off surfaces. They are often transient and will disappear on their own.
  • Reduce Moisture: Slime molds thrive in damp, shady environments, so reducing moisture and improving air circulation can help prevent their growth.

Conclusion

While pests and diseases like aphids and blight are more well-known, there is a whole world of lesser-known threats lurking in your garden. By expanding your knowledge of these less common garden pests and diseases, you can identify and manage them more effectively. The key is early detection, proper identification, and implementing integrated management strategies that suit your garden's unique needs.

With a proactive approach and the right tools, you can keep your garden healthy and productive, no matter what pests or diseases try to take root.