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Controlling and Identifying Hornworms

August 9th, 2011

 Judy McFarland, Solano County Master Gardener, wrote an article in the Summer 2010 issue of Seeds for Thought, about how to identify and control pesky hornworms.

The tomato hornworm is closely related to the tobacco hornworm and both attack tomato plants. It is the larval (caterpillar) stage of the hornworm life cycle that does the damage. They are characterized by a large horn on the posterior end of the body. A tomato hornworm has seven white stripes, while the tobacco hornworm has eight white V-shaped marks, on their sides. These larvae reach about four inches in length.

Tobacco Hornworm Egg
 

The adult form is a large moth that lays her eggs on the tomato leaves (one egg per leaf), like the photo above. The moth generally flies after dusk and is therefore rarely seen.

Hornworm droppings

As soon as you see defoliation on your tomato plant, check the leaves and ground for small black droppings, similar to those in the picture above. If you find these you have active hornworms! To get rid of them cut them with garden shears or step on them, or have a little fun and toss them on your roof for the birds to eat! Beware that if you get rid of hornworms once, they will most likely come back again as they generally live two life cycles in one tomato growing season.

If you are unable to get rid of them by hand, you can try to gain control with Bacillus thuringiensis (or Bt for short), which is a naturally occurring bacteria that causes disease in only the larva of moths and butterflies. That does mean if you use Bt, you will also put whatever butterflies come to your garden at risk.

Hornworm pupa

After tomato season, it is very helpful to dig up the soil around the plants to locate and dispose of any hornworm pupae which migrate underground only to reemerge the following summer as moths and start the cycle over again. The pupae are hard shelled, brown, and shiny and can be 2.5″ in length. They also have a curved appendage at one end that resembles that handle of a pitcher.

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Getting Rid of Squash Bugs and Stink Bugs

August 8th, 2011

Stink and squash bugs can ruin a perfectly good summer crop, but we have tips on how to prevent that from happening. Elaine Haire, Placer County Master Gardener, wrote an article for the Summer 2001 issue of The Curious Gardener on how to prevent, identify, and remove the pesky critters from your vegetable garden. Click here to see the full article.

STINK BUGS

Consperse stink bug

Named for the strong odor they give off when disturbed. stink bugs are shield-shaped with a large triangle on their backs. Consperse stink bugs are speckled grey and brown and prefer fruits and vegetables. Infested pears or peaches will develop “dimples” or depressions around the feeding sites, while infested tomatoes will have a smooth skin but with green or yellow discolorations on the fruit.

Harlequin stink bug

The harlequin stink bug has very distinctive black and red markings and prefers broccoli, cabbage, or radishes. This bug will leave yellow or white blemishes on the leaves where they feed.

Photo of two-spotted stink bug.

One of the good guys! Two-spotted stink bug.

There are two stink bugs that are actually beneficial to your garden, so watch out for the two-spotted stink bug and the rough stink bug as you want to leave these guys alone!

Rough stink bug

SQUASH BUGS

Squash bug

These bugs are grey/brown with orange around the edge of their bodies. They feed on squash and pumpkins. The first sign of damage is small brown specks on the leaves, which left untreated will eventually cause the plant to turn yellow and die.

CONTROL METHODS

For the squash bug, try to plant resistant varieties of the crops they like, for example: the butternut, royal acorn and sweet cheese squashes are all squash bug resistant. Consider planting nasturtiums or marigolds as they will attract squash bugs away from your crops. For further prevention, apply and remove row covers before the first bloom. Also look for shiny brown egg masses on the underside of leaves and destroy them.

To control the stink bug, look on leaf surfaces for clusters of barrel-shaped eggs to smash. Take a second to inspect these egg masses for darker colored parasitized eggs. Be sure not to destroy them unless there is a jagged emergence hole. If they are not parasitized, go ahead and squash them. Pheromone traps are also available for the detection of stink bug migration.

For prevention of both bugs, consider planting insectary plants near the susceptible crops which will provide nectar and pollen to attract natural eneimes such as the tachinid fly to prey on squash bugs or the parasitic wasp to kill stink bugs. Attracting birds to your garden is another helpful way to get rid of both bugs. Garlic based materials can be used as repellents.

During the growing season, remove weeds, dead leaves and garden debris to deprive these bugs of a place to hide.

After the growing season, reduce overwintering hiding places by removing all debris, and destroying crop residue by disking or composting.

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Fighting Pests with…Pests!

August 2nd, 2011

Thanks to an article written by Peggy Tharp, Nevada County Master Gardener, in the Summer 2003 issue of The Curious Gardener, we now know of two insects that are on our side! Both the lady bug and green lacewing help keep our gardens pest-free. Read on to find out why.

COCCINELLIDS

Adult Ladybug

More commonly known as ladybugs, coccinellids are shiny and often brightly colored, with black, red or orange markings. The ladybug larvae are alligator shaped, meaning broad in the middle and tapering to the tail. They are black or grey with red, orange, yellow or white spots and many have spines or are covered with wax.

Ladybug Larvae

No plant-feeding ladybugs are considered pests in California. The young larvae usually pierce and suck the contents of their victims, while the older larvae and adults chew and consume the entire prey. A ladybug’s insect of choice includes: aphids, mealy bugs, mites, scales, and whiteflies. Adult ladybugs can consume up to 100 aphids a day!

Fortunately many ladybugs can make it through the winter as adults by nesting in protected spots on or near the host plant. Plants that attract ladybugs are buckwheat, corriander, dill, fennel, marigold, sunflower, tansy, yarrow, and calendula.

LACEWING

Adult Green Lacewing

Lacewing have slender, green bodies, lacy wings and golden eyes. The adults are night flyer’s and attracted to light. Lacewings particularly love nectar and pollen but also feed on aphid honeydew. The larvae which are sometimes called aphid loins, gorge themselves on various small, soft-bodied insects such as aphids, scale crawlers, mealy bugs, whiteflies, leafhoppers, psyllids, small caterpillars and insect eggs.

Lacewing Larvae

The adult female lacewings make it through winter on leaf litter, while laying their eggs on slender white stalks on the leaves or twigs in the vicinity of the prey. The larvae then arrive in 3-6 days and are tapered at the tail and flattened with distinct legs and long mandibles used for snatching up prey.

Plants that attract lacewings are: angelica, caraway, coreopsis, cosmos, dill, fennel, Queen Anne’s lace, sunflower, sweet alyssum and yarrow.

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Reduce, Reuse, Recycle

August 1st, 2011

Did you know that by mulching with yard waste, we can reduce about twenty percent of the solid waste in landfills?

Jackie Kneeland and Sue Borden, both Placer County Master Gardeners, wrote the article titled “Reuse What Grows in our Yards,” in the Summer 2003 issue of The Curious Gardener, which describes five different methods for the low maintenance gardener to create compost used for mulching. Click here to read the full article.

Compost is not a fertilizer, but rather a soil conditioner. Composting helps to prevent the nutrients from becoming chemically bound in the soil and not available to the roots of the plant. By grinding garden waste, leaves, and small branches into pieces and using them on top of the soil around the plants, we conserve water, suppress weeds and protect roots from extreme soil temperatures.

Here are five ways to compost with much less space and effort than traditional composting:

OPEN AIR COMPOSTING

Open air composting consists of scattering small piles of yard waste around your garden. Make piles in the corner of your garden or near recently pruned shrubs. These small piles should not contain food scraps and will not decompose as fast as the larger traditional compost piles. Consider throwing alfalfa pellets or aged plant eater manure on the piles to supply them with the extra nitrogen that would come from the food scraps.

CLOSED AIR COMPOSTING

Closed air composting consists of composting in one small area of the yard. Use kitchen scraps and yard waste in a solid plastic container with a tight fitting lid, that is open on the bottom to the soil. You can even use an opened black plastic bag to tightly cover the pile (or better yet, just toss your scraps into a black plastic bag, cut a hole in the bottom and leave that in the sun). Do beware closed air composting is more likely to cause odor problems than some of the other options!

Meandering Trench Composting

SOIL INCORPORATION (3 Methods)

  1. Post-hole Composting- Dig a hole with a shovel or post-hole digger, add kitchen scraps, and cover with at least eight inches of soil. These holes should be made in the garden in between plants or around the drip line of a tree. These composting holes hold moisture, which will eventually leach a weak compost tea into the soil.
  2. Meandering Trench- Dig a short one foot ditch, chop yard trimmings and food scraps, and mix them into the soil in the bottom four inches of the trench. Resume digging the trench until the materials are covered and a new trench is formed.
  3. Pit and Trench- A three season rotation of soil incorporation that includes:
  • 1st season: The garden includes a trench to fill with food scraps, a row for growing crops and a third row to use as a path.
  • 2nd season: Use the fertile soil in the former compost trench to grow crops, use the former crop row as a path and loosen the former path to use as a new trench.
  • Finally:  After three years the cycle starts again.
Trench Composting

When creating any kind of compost pile, avoid using material that re-sprouts, such as willow, alder, and Bermuda grass.

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No Nutsedge Here

July 19th, 2011

Nutsedge is an aggressive weed, that most closely resembles grass. 

If you feel you are constantly fighting this weed to no avail, check out this article by Willa Pettydrove, Solano County Master Gardener, in the Summer 2007 issue of Seeds for Thought newsletter. Click here to read the full article or read on to see an abbreviated version that includes tips for what and what not to do.   

Immature nutsedge

What works   

  • Nutsedge loves water-logged soil so an easy fix is to correct your irrigation and soil drainage problems.
  • Prevent further tubular growth by removing the young nutsedge plants, which will only have five to six leaves. Simply pulling the weeds will work fine, but it is most effective to hoe by hand.
  •  If tubers are present, repeated removal of top growth will help to keep them under control as it is essentially starving the plant. Note that mature tubers (nutsedge with more than six leaves) can resprout as many as 10-12 times! These new sprouts will be weaker than the previous ones but they will gradually work together to resupply themselves unless removed.
  • If a plant is small the best way to remove them is to dig, by hand 8-14 inches deep to remove the whole plant. Remove and destroy any and all tubers (do not put them in your compost!). If you have nutsedge in smaller patches of turf, it is best to dig out a patch that is at least eight inches deep, refill, and then seed or sod the patch.
Left uncontrolled, nutsedge can form patches that spread more than ten feet in diameter.

What won’t work   

  • Using a tiller to destroy mature nutsedge. This technique will only cause the infestation to spread because it moves the tubers around in the soil, allowing them to resprout if they are strong enough. However, repeated tilling in small areas before the nutsedge matures will reduce populations
  • Systemic herbicides, like glyphosate, are a common misplaced effort of destroying the plant but because the herbicides really only touch the leaves, the tuber remain unaffected. Glyphosate might work on the younger plant in which the tubers have not formed.
  • Black plastic mulching won’t do the trick as the sharp, pointy leaves will go right through.

Nutsedge with tuber

   

**A tuber, as defined byMerrium-Webster, is a short fleshy usually underground stem bearing minute scale leaves each of which bears a bud in its axial (where the small stem joins the larger one) and is potentially able to produce a new plant.

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composting is easy…no really, it is!

July 18th, 2011

Thanks to Christine Smith and the Placer County Master Gardener’s Summer 2005 issue of The Curious Gardener, we have great instructions on how to build and understand a compost pile!

There are four basic things needed for this kind of compost pile: browns, greens, air, and water. This means your pile should be located in a open area, near a water source, and should have equal parts green and brown.

“Brown” is something dry and high in carbon. There are lots of examples of brown; you can include dead leaves, cut brush, wood shavings, and straw. From inside the house you can use newspaper, paper egg cartons, junk mail (but only the non-slick or shiny paper), paper towels, as well as the paper towel tubes, and other forms of corrugated cardboard.

The “greens” will come from things that are moist and high in nitrogen. Grass clippings, or feces from animals that only eat plants, and from the kitchen you should save tea bags, citrus rinds, and fruit or vegetable trimmings.

Proper air and water balance within a pile is essential for rapid decomposition to occur. Turning, lifting and stirring are the most efficient ways to aerate a compost pile. The pile should be moist to the touch, but yield no liquid when squeezed, similar to a wrung-out sponge. Also the smaller the pieces, the faser the composting process, so pieces should be between 1/2″ to 1 and 1/2″ in size. To achieve this size, try shredding the compost ingredients before adding them to the pile or using a power lawn mower with a bag attachment to reduce the particle size and increase particle surface area. Altogether though, the pile should be about 3′x3′x3′ or one cubic yard.

Assembling the pile:

  1. Start with 4-6″ of brown
  2. Add 4-6″ of green
  3. Mix the layers using a spading fork or shovel
  4. Check pile for moisture- grab a clump of material and squeeze it, if it sticks together you’re good to go, if not sprinkle a little water on the pile and re-stir

Repeat steps 1-4 until the pile is 3′x3′x3′, always checking moisture content after each layer is added. After about 2 days the pile temperature will be between 110-140F , which could cause steam to come off the pile but this means that composting is happening! On day 3, turn the pile and check the moisture, and this is to be done every 3 days from this point forward. Temperature will continue to rise, which kills weed seeds, insect eggs and diseased organisms. Using a compost thermometer check the temperature and if it rises above 140F, cool it off by turning the pile. 

After 2 weeks the pile temperature will drop as composting slows and at this point the compost should be dark brown and crumbly with an earthy scent.

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The Buddy System

July 12th, 2011
Jan Bower, Yolo County Master Gardener, explains how the planting buddy system or companion planting works in her article from the 2010 Summer issue of The Yolo Gardener. Click here to read the full article.

Jan explains companion planting is the idea that some plants benefit from growing in close proximity to others, it’s nature’s ”buddy system.” Some known benefits of the buddy system are better growth, higher yield, pest control and weed repression.

The Three Sisters buddy planting

This idea originated with the Native Americans, specifically the Iroquois, who planted corn, beans and squash together calling the combination “Three Sisters.” Unbeknownst to them this threesome worked so well together because squash takes nitrogen out of the soil, while beans put it back. Lastly corn creates shade which is needed for good production of squash and beans.

Here is a list of was to create beneficial plant associations:

  • Trap Cropping- Plant a secondary plant that attracts pests away from the main crop
  • Symbiotic Nitrogen Fixation- Reduce the need for nitrogen based fertilizers by planting legumes and/or clover which add nitrogen back into the soil
  • Physical Spatial Interactions- Plant your garden with a tall, sun loving plant and a low, shade loving plant. For example, plant corn or sunflowers with squash or lettuce.
  • Beneficial Habitats- Create a habitat that attracts and supports a population of beneficial insects.  To do this reduce pesticide use and provide host insects, nectar, pollen, water and shelter. Beneficial insects include: ladybugs, lacewings, hover flies, spiders and wasps.
  • Security Through Diversity- Mix different types of plants in the garden so if pests or adverse conditions destroy some plants, others will remain.
Ladybugs helps us get rid of those pesky aphids!

Here are some buddy planting examples:

  • Mint, rosemary, and garlic create a strong scent that repels aphids, ants and other pests from members of the cabbage family (broccoli, turnips, radishes) as well as roses.
  • Beans and peas should never be planted near the members of the onion family (garlic, chives, leeks and shallots). The excessive nitrogen given off by beans and peas encourages more foliage and less bulb. Also the sulphurous gas given off by onions is toxic to peas. Instead try planting beans and peas with carrots!

Do you plan your garden to incorporate companion or “buddy” plantings? Let us know combinations you like.

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