Week.9. Nematodes & Mollusks

Question 1

______ Are:

-Unsegmented roundworms.

-Feed on bacteria, fungi, vertebrates & invertebrates.

-Some are beneficial because they kill pest insects or other plant parasitic nematodes.

Answer 1

Nematodes

Question 2

Plant feeding nematodes develop through six stages:

Answer 2

Eggs, Four juvenile stages, Adult

Question 3

Many _____ can develop from eggs to egg laying adults in 3-4 weeks when soils are warm.

Answer 3

Nematodes

Question 4

_______ require moist environments to feed and reproduce.

Answer 4

Nematodes

Question 5

During adverse conditions such as dry soil, cold temperatures, or lack of host, some species of _______ develop resistance to drying out and become inactive.

Answer 5

Nematodes

Question 6

Dormant ______ can survive a year or more dormant.

Answer 6

Nematodes

Question 7

Signs of ______ include:

-General Decline of plant.
-Yellowing of leaves.
-Darkened roots with lesions.
-Root galls, stubby, or stunted proliferated roots.

Answer 7

Nematodes

Question 8

For ____ diagnosis, cut open any galls and use hand lens or microscope to examine for the presence of pinhead-sized shiny white females. For confirmation send root and soil to laboratory.

Answer 8

Root-knot nematodes

Question 9

For ____ initial diagnosis, tear symptomatic tissue into small pieces ad place in a glass dish. Add enough water to immerse the plant tissue, an them cover the dish to reduce evaporation. After 24 hours inspect water under strong light using a 10x lens or higher magnification. Nematodes appear as tiny strands moving in the water.

Answer 9

Foliar Nematode

Question 10

Nematodes are difficult to manage because in most situations you cannot directly reduce their numbers. Most of the practical methods of management are preventative. AND…

Answer 10

-Good sanitation practices.
-Grow plants that are resistant to nematodes (or not susceptible)
-Provide good cultural care and appropriate growing conditions.

Question 11

Soil or runoff with ____ will transfer them to your plant.

Answer 11

Nematodes.

Question 12

To avoid spread of _____
-Sanitize tools after use.
-Work in uninfected areas first, before moving.
-Consider replacing severely damaged plants with resistant plants.
-In nematode infested areas consider fallowing the soil (keeping plant and weed free) for 4 years before re-planting. (Ensures dormant nematodes die off)

Answer 12

Nematodes

Question 13

No chemical nematicides or soil fumigants are available to home gardeners or professional gardeners.

Answer 13

Pesticides and fumigants may be available to certified applicators in certain commercial/agricultural applications and are costly and rarely used.

Question 14

Nematodes cause more damage in sandy soils and are less problematic in silty or clay soils.

Answer 14

Nematodes cause more damage in sandy soils and are less problematic in silty or clay soils.

Question 15

Solarization can help clean the 6” layer of soil and will temporarily reduce nematode levels.

Answer 15

Does not prove effective to control nematodes in perennial or woody plants, but effective in annuals or short-lived plants with shallow roots.

Question 16

Certain plants can suppress certain types of nematodes. Example: Growing a solid Marigold crop during a season and then incorporated into the soil will reduce the nematode population.

Answer 16

Other plants know to suppress nematodes include barley, certain legumes such as clover and vetch, and perennial rye.

Question 17

Certain natural enemies and pathogens of nematodes can keep populations in control but are not enough to prevent susceptible plant damage.

Answer 17

Certain natural enemies and pathogens of nematodes can keep populations in control but are not enough to prevent susceptible plant damage.

Question 18

The most detrimental mollusk pest in the landscape are _____.

Answer 18

Snails

Question 19

_____ are mollusks that glide along on a muscular foot that secretes a mucus.

_____ need moist conditions.

Answer 19

Snails.

*Snails have spiral shells and slugs don’t, however their management is similar.

Question 20

Snails & Slugs chew irregular holes in leaves and, clip off succulent plant parts and can chew fruit and tender bark.

Answer 20

Dry silvery trails and chewed plants indicate snail activity.

To locate snails in the garden search for protected spaces

Question 21

Snails are most active during damp periods during early day or evening.

Answer 21

Snails are active year-round Coastal Southern California with wet and mild winters.

Question 22

During cold weather snails hibernate in topsoil

Answer 22

During hot and dry weather, they can seal themselves with a parchment like membrane and often attach to shade tree trunks, fences or walls.

Question 23

The brown garden snail is the most common of the pest snails is the _____.

Answer 23

Cornu apersa.

Question 24

Milk snail or ____ ____ is also present in Orange County.

Answer 24

Otala lactea

Question 25

Snails have tens of THOUSANDS of tiny teeth on a tongue-like apparatus called a radula (RAD-you-luh). Snail teeth are made of a protein called chitin instead of enamel.

Answer 25

Snails don’t bite. A radula is like a cheese grater, and it works by scraping food into their mouths like a conveyor belt instead of chewing it.

Question 26

To Reduce Snail/Slug Population:

-Avoid watering frequently.

-Water early in the day so surfaces can dry by the evening.

-Reduce hiding places.

Answer 26

-Look for them in hiding places.

-They are common in thick ground cover areas like honeysuckle or ivy.

-Hand picking can be an effective mean of control. (Use gloves crush and dispose).

-Place traps and monitor regularly.

Question 27

Management of Snail/Slug Population:

-Beer container attract slugs. Keep fresh and refill at least twice a week. This method can be a lot of work and is not too effective

-In orchards copper barriers can be placed around trees to prevent them from reaching fruit. Alternative barriers are the Bordeaux Mixture (copper sulfate and hydrated lime) repel snails too.

Answer 27

-Skirt tree branches off the ground to prevent snails crawling up the trees and feeding from the fruit.

-Biological control is effective. Predators of snails include decollate snail, ground beetles, reptiles, birds, and mammals.

Question 28

Predatory _____ Snail _____ _____consume young to half grown brown garden snails.

Answer 28

Rumina decollata

Question 29

Rumina decollata predatory snail:

-Has been effective in snail control in citrus orchards. It may take up to 4 years to get full control. (Do not use chemical baits as they kill both).

-Decollates also feed on succulent young plants so caution has to be taken if released in herbaceous ornamental gardens.

Answer 29

-Decollate snail introductions are only permitted in certain counties of central and southern California.

-Release in other areas is illegal because of the potential impact on native snails.

Question 30

-Chemical baits temporarily reduce populations of snails and slugs.

-Most effective when combined with other management strategies that aim to reduce hiding areas, control irrigation, and conserve natural enemies.

-Metaldehyde baits are poisonous to other mammals and can kill dogs. Avoid using.

Answer 30

-Iron based baits are safe for pets and wildlife.

-Timing is critical for bait application. Spot applications where mollusks are active, instead of widespread applications are preferred. Irrigate before the application to promote snail activity.

-Avoid watering once baits are applied as excess moisture will rapidly degrade baits.

-Do not apply if heavy rain is expected.