Category: Greenhouse IPM

Treatment for black fungus gnats

Black Fungus Gnat – IPM Treatment

Fungus gnats
Fungus Gnats on Cacti

GNATS

We all know what a gnat is. Most likely you have had a few gnats flying around your home, more commonly known as “fruit flies”. But fungus gnats are your gardens worst nightmare! They are small flies that infest soil and potting mix and lay their eggs in your container gardens as well. Their eggs can lay dormant in soil for weeks and then release these nasty little larvae that wreak havoc on your plants. Their larvae primarily feed on fungi and organic matter in soil, but also chew into roots and can be a problem in greenhouses, nurseries, potted plants and interior plants. Adult fungus gnats may emerge from houseplants and become a nuisance indoors too.

Fungus gnat larvae
Fungus Gnat Larvae
Fungus gnat Adult
Adult Fungus Gnat

 

 

 

 

 

 

TREATMENTS

There are a bunch of organic and chemical treatments for fungus gnats. The organic solutions include:

Hydrogen peroxide w/ no additives, Boiled grapefruit rind, Neem oil and a plethora of IPM.

We discovered we had gnats in our indoor Sunglo greenhouse after purchasing a bag of store bought miracle soil. It has been a HUGE problem. At least 100 plants have been ruined. So we researched online and came to the conclusion that we would try nematodes.

What are nematodes?

fungus gnat
Microscopic Nematode

The nematodes or roundworms constitute the phylum Nematoda. They are a diverse animal phylum inhabiting a very broad range of environments. Nematode species can be difficult to distinguish, and although over 25,000 have been described, of which more than half are parasitic, the total number of nematode species has been estimated to be about 1 million. Unlike cnidarians and flatworms, nematodes have tubular digestive systems with openings at both ends. Nematodes have successfully adapted to nearly every ecosystem from marine to fresh water, to soils, and from the polar regions to the tropics, as well as the highest to the lowest of elevations. They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in locations as diverse as mountains, deserts and oceanic trenches. The earth benefits from these microscopic worms. They are pretty much everywhere!

NEMATODE TREATMENT

fungus gnat
A Fungus Gnats Worst Nightmare!

There are lots of brand of nematodes to buy but we settled on this baby. Above. The nematodes come wrapped in a soft wet sponge ready to swim their way into your soil and eat the fungus gnat larvae!

fungus gnat
Remove sponge from bag..

 

fungus gnat
Dunk sponge into a watering can.. and water all your plants.

By dunking the sponge in water and swooshing it around a bit, it will release the microscopic nematodes into the water and allow them to be transferred into your infested soil. One they have broken the soil barrier the nematodes are free to wreak

havoc on the fungus gnat larvae! Too bad they are microscopic. It would be pretty neat to see 🙂

CONCLUSION

The nematode treatment worked, along with sticky tape but only for a week or so. It was difficult keeping our greenhouse contained. The gnats had too many places to hide in our building and were able to fly freely in and out of the greenhouse. In a different situation the nematodes, I’m sure, would have wiped out the larvae and our problem would have disappeared. We eventually cleaned out the entire greenhouse, cleaned all pots and containers, threw away all the dirt that was sitting around and moved most of the plants outside for a weekend to try to abolish the pesky gnats! And so far we’ve gotten rid of ALMOST all of them. The orchids we have in the greenhouse now are doing pretty well – See picture below. There are still a few gnats buzzing around but they have not harmed our orchid collection. We definitely learned a lesson from this… no more store bought generic soil! And to keep the greenhouse as clean as possible when planting seeds. The next time we see the first signs of gnats we’ll reach into our Google arsenal and find the next best treatment.

fungus gnat
Our display greenhouse after being cleaned out

Other pest problems? Click here for thrip information. Click here for aphid & white fly treatment. And for more information about greenhouses and greenhouse gardening visit our Facebook page!

 

Ladybug pest control

Ladybugs – Your best ally in the fight with aphids!

Ladybug

Ladybugs –

 Let’s learn a little bit about these pest eaters. Ladybugs have many names. Such as lady beetle, Asian lady beetle, multicolored Asian lady beetle, ladybird and many more. They are actually not bugs but are beetles. Ladybird Beetle is the correct name but I still like “ladybug” There are about 5,000 species of ladybugs worldwide, only 400 are native to North America. The convergent lady beetle is the most common species.

Ladybugs are widely used as a form of natural pest control. Aphids seem to be the top food choice for them but they also eat scale insects, mealy bugs, mites, white fly and other soft insects. A fully grown hungry ladybug can eat 50 aphids a day! They could eat 5,000 aphids in their lifetime in both larvae and adult stages.

 

LadybugsAphids-

Aphids are the most common garden pest insect and they feed on almost every type of plant. There are many different species of aphids but they all seem to have the same goal in mind… destroying you’re garden! They feed in colonies which is why they are so destructive and fast.

Signs of aphids are dried and colorless leaves and curled leaf tips. Aphids usually can be found on the underside of leaves and close to the top where the most nutrients can be sucked from the plant. They are savage little things and need to be dealt with as fast as possible.

LadybugsPest control-

Here at our Kent, WA. Sunglo office and warehouse we have a few greenhouses on display and like to grow plants and veggies ourselves, so we take advantage of the opportunity by growing a few things here and there. We bought a few herb plants from a home and garden depot only to find aphids on them!

We decided to try ladybugs for pest control. And boy let me tell you… it was awesome! We were able to purchase 1500 bugs online and they arrived within 5 days, let them free in our small lean-to greenhouse and within 15 minutes almost every aphid had disappeared! Overall I would 100% recommend ladybugs to get rid you of your pest nuisance! They are cute, inexpensive and best of all non-toxic! We freed most of them by keeping the doors wide open but a few are still around, stalking their next aphid meal.

Ladybugs

To learn about another common pest; thrips – click here.

Thrips: Know thy Enemy

Thrip AdultToday’s post takes a closer look at and offers some suggestions for controlling one of the most widespread and detrimental species of thrips – Western Flower Thrips. Sometimes, when we strive to create the perfect growing environment for our plants we provide an optimal habitat for some nasty pests. Thrips thrive in warm environments protected from harsh outdoor conditions and their illusive nature can make them difficult to spot before the damage is done. Identifying the signs early and acting accordingly is the key to thrip control. The information below is a brief outline to aid you in doing so.

Description
Adult WFT are less that 2 mm long.  The female adult ranges in color from light yellow to dark brown.  Males are slightly smaller and are light yellow in color.  Both have slender cylindrical bodies and two sets of clear, nearly veinless, narrow wings that have dark, hairy, fringes.  The wings also have two complete rows of setae.  The larvae are tubular shaped, less than 1 mm long and are translucent white to yellow in color.  They resemble the adults but do not have wings until the third instar.

Life Cycle
The annual WFT life cycle varies depending on environmental conditions.  In cold climates such as the Northern U.S. they cannot over winter outdoors.  In slightly milder climates they can over winter in weed hosts, plant debris, and soil.  In a greenhouse setting their life cycle is continuous and overlapping.  It does however consist of these five main stages regardless of environment: egg, two larval instars, prepupa and pupa instars, and finally adult.
The population increase and time required for development of each generation is highly dependent on environmental conditions and the nutrient levels of the host plant.  The following account is based on an average host and temperatures between 68 and 98 degrees F.  The female can lay between 130 and 230 eggs.  The eggs then hatch in 2 to 4 days.  During both instars of the larval stage the larvae feed on plant material and then enter the non – feeding prepupal stage after 3 to 6 days.  The pupal stage is also non – feeding and lasts for 1 to 3 days.  The adult then emerges and can feed and reproduce for a subsequent 30 to 35 days.

Petal DiscolorationDamage
WFT damage is caused by feeding and oviposition, as well as indirectly through virus transmission.  The female’s ovipositor has two serrated blades that are used to cut through the plant epidermis and deposit eggs into the tissue.  This can cause scars on the leaves and fruit of some crops and decrease their economic value.  Feeding damage is caused by both the larvae and adult thrips and can occur on fruit, flowers, flower buds, leaves, and leaf buds.  WFT use their modified mouthparts to puncture the plant epidermis, inject saliva, and siphon out the cell contents.  The damaged plant cells collapse, resulting in distorted growth, silver patches, and scars on expanded leaves.  Flower petal damage can appear as dark streaks in lighter flowers and lighter streaks in those of a darker color.  Feeding on the leaf or flower buds can cause them to abort, and when they do grow they can exhibit distorted growth.  This can make diagnosing thrip problems difficult because the symptoms will not be evident until the bud opens.
Western flower thrips are also notorious for being the primary vector of viruses such as tomato spotted wilt (TSWV) and impatiens necrotic spot (INSV).  Adult thrips cannot acquire the virus and it is not passed on to offspring so infection occurs during the larvae phase as a result of feeding on infected plant tissue for about thirty minutes.  After three to eighteen days the virus can be passed on when the insect feeds for only five to ten minutes on another host.  Thrips retain the infection until death and the concentration of the virus increases as it replicates throughout the vector’s lifetime.  The virus was historically common in the western and southwestern United States, but began spreading rapidly in the 1970 and ‘80s with the spread of western flower thrips.

Control

  • Mechanical

As with any integrated pest management strategy a thorough monitoring and identification system is the first priority.  Yellow and blue sticky traps attract thrips and can be used to reduce and monitor pest populations.  Exclusion acts as a first defense against thrips.  All plant material being brought into the greenhouse should be thoroughly inspected before hand.  Production areas should be sealed tight and limited to authorized personnel.  This can be achieved by the use of door seals and thrip preventive netting over all areas where external air is allowed to enter the greenhouse.

  • Cultural

Because of the wide host range of WTF it is important to remove all weeds both inside and in close proximity to the greenhouse.  These serve as safe harbor for thrips and viruses when a non – susceptible crop is being grown.  If the weed removal is thorough then alternating between susceptible and non – susceptible crops can also prevent pest problems.  A layer of hydrated lime thick enough to cover the soil on the greenhouse floor can prevent algae, weeds, and insects.  Some growers also remove all plant material between crops for a period of seven days to allow adults to emerge from the pupal stage and then kill them with insecticides or elevated temperatures.  A continuous temperature of 102 degrees F for two days will kill the adults.

  • Biological

Predacious minute pirate bugs, mirids, and mites have all been used to control WFT populations as well as fungi.  The minute pirate bugs and the predacious mites both go into diapause under short day conditions and so have not been as affective in the winter.  However, both have proven to be able to derive enough nutrients for development from WTF alone.  The mites do best on plants that provide a surplus of pollen for diet supplementation in order to reach a sufficient control population faster.  The time it takes for all three predator populations to establish themselves and increase to an effective control level is the main limiting factor.  The rapid development and proliferation of WFT usually exceeds that of these predators in the case of most crops.  Fungi such as Beauveria bassiana and Verticillium lecanii have also been used to develop registered biological controls.  The spores infect the pest through contact with its cuticle and are not limited by environmental conditions or the crop being grown.

  • Chemical

WFT are commonly controlled with endosulfan, chlorpyrifos, bendiocarb, and synthetic pyrethrinoids, but their spread has, in a way, been aided by pesticides.  They have the ability to quickly develop a resistance, and when native varieties of thrips and predators are eliminated WFT face less competition and thrive in the new areas.  If a chemical control is going to be used it is recommended that the pesticide class be rotated every generation (about 14 days) to help prevent pesticide resistance development.  The pupa and eggs are also unaffected by sprays so it is important that the application program lasts long enough to eliminate emerging larvae and adults.