The state of California is known for its agriculture; the temperate climate makes it the perfect growing environment. With the crops come a group of both exotic and invasive pests who threaten the health of the plants and cost the growers big dollars. The Asian Citrus Psyllid is a well-known invasive pest in California; this pest carries the bacterial plant disease Huanglongbing (HLB) which can kill the citrus trees.

The Mediterranean fruit fly, also known as medfly, is an exotic pest considered to be a major threat to the state of California’s agriculture. The medflies lay eggs under the skin of fruits and vegetables; the eggs hatch and the medfly larvae remains inside the fruit or vegetable. This of course makes the fruit inedible and it’s now easy to transport infected fruit all around the world. Mediterranean fruit flies are native to Africa but can now be found in counties all around the globe; the medfly was first detected in the continental US in 1929.

The Mediterranean Fruit Fly has been found infesting over 300 varieties of fruits and vegetables. California crops threatened by the fly include orange, plum, walnut, apple, apricot, avocado, bell pepper, fig, grape, grapefruit, lemon, lime, melon, nectarine,  peach, pear, persimmon, pomegranate, tangerine, tomato and grapefruit.

So what is being done to control the Mediterranean Fruit Fly? Sterile Insect Technique (STI) and quarantines. STI is the process of releasing sterile insects to disrupt the reproductive cycle of the insect. STI has been used successfully in the past and is used when medflies are found around the area. It is an ongoing process of STI and quarantines to make sure this species of fruit fly does not become established in the United States.

What can you do to help? Avoiding shipping fruits and vegetables into the state of California unless they have been looked over by an agricultural inspector. Also, it may seem like common sense, but cooperate with quarantine restrictions, they are there for a reason.

The USDA has a site specifically designated as an invasive species information center. It’s interesting to see the invasive animals, plants, aquatic species and even microbes affecting not just California but states around the US.

{photo credit: sarsifa}

Did you know it is estimated over 12,000 species of ants crawl this planet? It’s true and about 200 species of ants call California home.

The most common ant in California is the Argentine ant but it is not indigenous to The Golden State. The Argentine ant is native to southern South America; like many other species of pests, the ant was unintentionally brought to Europe, Australia, Hawaii, and of course, North America.

These ants are one of the world’s worst invaders and part of that is because of their ant mega-colonies. It is believed there is a huge colony in California stretching for 560 miles; this colony is often referred to as Californian large. Ant mega-colonies have become a major issue because they often attack crops and affect animal populations.

For instance, Argentine ants may be responsible for the decline in the coast horned lizards in California. Argentine ants dine of several species of ants that primarily make up the diet of these lizards. The large number of ants belonging to the Argentine ant mega-colonies just devour the ants needed to sustain the coast horned lizard population.

Basic facts about Argentine ants:

• Dark colored
• Worker ants are just 3 millimeters long and queen ants vary from six to 12 millimeters in length
• Prefer sweets including fresh fruit
• Crawl quickly in clear-cut trails
• Possibility of millions of ants per colony

Argentine ants seek refuge in houses and buildings because they are looking for food and/or water or they may be seeking shelter after a heavy rain. Controlling Argentine ants can be a daunting task since killing the workers isn’t effective as a queen will just produce more workers AND one colony can have multiple queens; contacting a local exterminator is often a good idea. But if you would like to try some DIY pest control, there are some options.

Slow acting poison baits typically work best since the bait will eventually make it to the queen.  There is a homemade ant bait recipe out there that many people have had success with; dissolve 1/4 teaspoon of boric acid powder and 1 tablespoon of white sugar with 3 tablespoons of water. Place the bait in an area the ants will visit. This method of pest control can take four or five days to work since the bait needs to make it through the entire colony.

Proper sanitation and caulking ant entrances are both good ways to avoid an Argentine ant invasion.

{Bottom right photo credit: Matthew Townsend}

What is it?

Sudden Oak Death, also referred to as SOD, is caused by the oomycete plant pathogen Phytophthora ramorum. The pathogen can kill a variety of oak species and can sicken other varieties of plants including the rhododendron and the huckleberry.

What are the symptoms of SOD?

-Dark sap “bleeding” from the base of the tree (see picture to the right)

-Leaves rapidly change from green to brown

-Fine dust from beetles boring through the bark and the wood

The above are just symptoms and can be associated with other tree diseases. The only way to be sure a tree is infected is by culturing the pathogen in lab. Also, the above symptoms are those found with species of oaks with the disease. Symptoms for other species of plants and trees may vary. View list of SOD host plants.

Where is it?

It seems the plant pathogen is localized to central coastal California but has also been confirmed in southern Oregon. A similar species has also been discovered in the UK and Europe.

Phytophthora ramorum may be influenced by climate including humidity and temperature which may prevent oaks in southern California from becoming infected.

How is passed from tree to tree?

It is not known how the pathogen is spread but there is some speculation. Other species of  Phytophthora are transmitted via air and water but many researchers think the pathogen for SOD can be carried on shoes, by pets and even vehicles. Commercial nurseries may also be a source transmission.

How can it be prevented?

Isolating any known infected areas is crucial to control. Be sure to clean your feet, your pet’s feet, camping gear, tools, etc… when moving from an area known to have the pathogen to an area that is not infected.

Also, minimizing damage to the tree trunk and large branches as well as pruning only during dry summer months when beetles and pathogens are least active can make the tree less susceptible.

How to treat it?

There is no known control for SOD. While some treatments are being used and showing slight signs of effectiveness, there isn’t a proven treatment. There is hope as other species of Phytophthora have been controlled with various fungicides.

This is just a brief overview of sudden oak death. For more information, refer to any of the credible resources below.

California Oak Mortality Task Force

Washington State Department of Agriculture – Sudden Oak Death

University of California  – Sudden Oak Death in California

You may be concerned with the pests in or near your house, but there is one single pest that is threatening California and could destroy the state’s citrus trees. The insect I’m referring to the is Asian Citrus Psyllid.

The Asian Citrus Psyllid (ACP) is an insect that feeds on the leaves of citrus trees, but the real problem with the ACP is the disease that it can carry. The disease is called Huanglongbing (HLB) and it is also referred to as Citrus Greening Disease. The insect has been found in California but HLB has not yet been confirmed in California and unfortunately the disease is impacting citrus industries in over 30 countries and even citrus trees in Florida. HLB is a bacterial plant disease that infects citrus trees which will eventually produce fruit that is bitter and inedible. There is no cure and the tree will eventually die.

It is so important to prevent this insect from bringing HLB into the state that a website has been created called California Citrus Threat; the goal of the entire site is to spread awareness about the Asian Citrus Psyllid, Huanglongbing and what to look for.

So what happens if you find a Asian Citrus Psyllid? Well according to the California Citrus Threat website if you find a ACP, contact your local agricultural commissioner (they have a look up tool using your zip code). If a tree on your property has the pest, it will be treated; if the tree has HLB, the tree will be removed to protect other trees on your property and throughout the state.

The pest in the picture to the left is a glassy-winged sharpshooter. The name is not made up but the insect is considered both exotic and invasive to the state of California, this pest has is even been seen in Orange County.

A pest that is exotic and invasive is a pest that is not a native species (insect, plant, etc…) and has rapidly spread throughout the region. Exotic and invasive pests can be intentionally or accidentally introduced. But many times it is very difficult to eradicate the species and can often cause environmental problems within its new home.

According to invasivespeciesinfo.gov, almost half of endangered and threaten species in the United States are impacted by invasive species. The same site mentions that one study estimates that invasive species cost more than $100 billion for the United States every year.

It’s interesting to note that species that are staples in our country such as rice, corn and cattle were once introduced and could be considered invasive and exotic. So it’s possible to say that there are pros and cons. But more often than not, the introduction of invasive and exotic pests should be avoided.

Here are a few easy steps to prevent a non-native species from becoming invasive:

• Avoid dumping anything from an aquarium into local ponds, streams, etc… This include plants, fish and invertebrate
• Burn firewood where you buy it…transporting firewood can move insects and other pests from one region to another
• When possible, use native plants in your landscaping
• Think twice when buying exotic pests such as pythons, parrots, etc… these animals can cause numerous problems including threats to safety and human health

Here’s a great resource for invasive and exotic pests. This site includes information and pictures for exotic insects, plants, weeds and other species. Invasive.org is also a great place to find related links and publications dedicated to invasive and exotic pests.