Root mealybugs are small rice sized white cotton-like insects that live in the soil of a plant. Instead of feeding on foliage sap like regular mealybugs, root mealybugs feed on root sap of the plant. It can be hard to initially spot an infestation, unless you are checking the roots. The main sign of a root mealybug infestation is an unknown decline in plant health. Declining plant health can happen for numerous reasons but it 's important to rule out root mealybugs. UK houseplants. (n.d.). Root mealybugs. Root Mealybugs. Retrieved February 20, 2022, from https://www.ukhouseplants.com/pests/root-mealybug. Root mealybugs are more dormant in the winter with the life cycle taking up to 4 months to get from egg to mature adult. In the summer, root mealybugs can mature from egg to adult in as little as a month. The white powdery areas in the above image show where the egg sacs are. Once the eggs hatch into nymph’s aka crawlers, the insects are ambulatory and spread easily. Do not use the same water between plants as nymphs can be transported via water. Due to the high mobility of these insects, it's recommended that you do not put any plants anywhere near an infested plant. Root mealybugs can be a vexing pest to deal with and can return after the infestation is gone. One method to dealing with root mealybugs is simply getting rid of the infested plants. Other methods include chopping the roots off completely and propagating, using systemic insecticides with the active ingredient imidacloprid, and soaking the roots in hot water. If you use the chop and prop method, I would recommend soaking the cuttings in alcohol spray solution for 10 minutes and using a soft-bristled old toothbrush to gently scrub down the stems/leaves. Do not reuse the same grow medium when repotting/propagating. Once potted up, add in systemic insecticide (granules or liquid). Note that using systemics is not a one-time application but will require periodic usage throughout the year. Alcohol spray: 1/2 cup isopropyl alcohol 70% 4 cups water The hot water bath method is effective if the temperature is 120F. To do this take the root ball of the plant and immerse it completely in the hot water for 10 minutes. This should be enough time to kill any living mealybugs on your plant. References: Hodgson, L. (2017, February 10). Root Mealybugs: Death From Below. Laidback Gardener. https://laidbackgardener.blog/2017/02/10/root-mealybugs-death-from-below/#:~:text=Root%20mealybugs%20are%20active%20all Bethke, J. (2013). Spring 2013: Hot Water Treatments to Control Pests. Ucnfanews.ucanr.edu; University of California, Division of Agriculture and Natural Resources. https://ucnfanews.ucanr.edu/Articles/Regional_Report_San_Diego_and_Riverside_Counties/Spring_2013__Hot_Water_Treatments_to_Control_Pests/
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There are hundreds of different Hoyas available to purchase. Not to mention there are so many interesting characteristics between different varieties and new hybrids coming onto the market. I thought I would share some of my favorites. H. manipurensis I absolutely love the shape of the leaves and find it to be unique among the Hoya genus. H. latifolia 'Pot of Gold' fka macrophylla This has been one of my all time favorites since I started collecting. The variegation between each leaf can vary greatly. Love the contrast of the leaves. H. AH-074 Such a lovely sport carnosa. Carnosa's tend to be fast growers and this is no exception. There are two clones of AH-074, one that is almost all silver and a second that is green and silver. I love the way the green and silver look together. H. sarawak Between the veins and large leaves this one is a 10/10 for me. H. villosa Wonderfully pubescent leaves with such amazing veins. Honorable mentions: There are basically way too many Hoyas that are amazing. I would also add in H. waymaniae for the velvety soft leaves and H. fitchii for the incredible veins. Scale are insects named for their shell-like wax casings that suck sap from plants. Scale, whiteflies, mealybugs, and aphids are a part of the superfamily Coccoidea. The most common types of scale are soft and armored. Soft scale tends to look more fluffy or gummy while armored scale is very waxy. Frank, S. (2021). Cottony maple leaf scale, Pulvinaria acericola, ovisacs on dogwood leaves. Cottony Maple Leaf Scales Producing Eggs. Retrieved February 18, 2022, from https://entomology.ces.ncsu.edu/2019/05/cottony-maple-leaf-scales-producing-eggs/. Armored scale is typically smaller than soft scale and appears flatter. This flatness can make it harder to identify on a plant. United States National Collection of Scale Insects Photographs, USDA Agricultural Research Service, Bugwood.org. (1979). Greedy scale (Hemiberlesia rapax). Retrieved February 18, 2022, from https://www.ipmimages.org/browse/detail.cfm?imgnum=5113037. A couple of key differences between the two types of scale are indicated by the following chart. Palmieri, M. (2013). Soft Scales Vs. Armoured Scales. Up to scale. Retrieved February 18, 2022, from https://www.landscapemanagement.net/up-to-scale/. Life cycle stages of scale includes egg, nymph aka crawler, and adult. The female scale insect will lay eggs underneath their scale covering. Once the egg hatches you have a nymph aka crawler. This crawler will move to a new spot to start feeding on sap. Once a crawler starts feeding, the shell will start developing and the legs disappear completely (in armored scale). It is generally understood that once a crawler picks a new spot that they do not move. Adult males are more similar in appearance to fungus gnats. Soft scale can produce asexually through a process called parthenogenesis. Armored scale usually mate sexually which requires the adult males to fly to the females. Scale has a fairly long life cycle of 3 or more months. King Quenson. (2021). Scale insect life-cycle. How to Manage the Scale Insects. Retrieved February 18, 2022, from https://www.kingquenson.com/ar/Company_News/How-to-Manage-the-Scale-Insects.html. An instar is just a phase between two distinct periods when an outer layer or covering is shed or added to. This helps to estimate the age of the scale. Held, D. (2019). Armored scale completed all three of the nymphal instars. Controlling Scale Insects and Mealybugs. The Alabama Cooperative Extension System. Retrieved February 18, 2022, from https://www.aces.edu/blog/topics/lawn-garden/controlling-scale-insects-and-mealybugs/. Scale damage on a plant can manifest in sticky honeydew (from soft scale), black sooty mold forming on honeydew, yellowing/dying leaves, and dying leaves/branches. Stevens, R. E., & Cranshaw, W. (2020). Honeydew, excreted by brown soft scale, which has collected on a nearby leaf. Brown Soft Scale – A Common Insect Pest of Indoor Plants – 5.599. Colorado State University Extension. Retrieved February 18, 2022, from https://extension.colostate.edu/topic-areas/insects/brown-soft-scale-a-common-insect-pest-of-indoor-plants-5-599/. Nature Garden. (n.d.). Mock-orange leaves covered with armored scale insects. Sooty mold, techniques and organic treatments to avoid it. Retrieved February 18, 2022, from https://www.nature-and-garden.com/gardening/sooty-mold.html. Combatting scale once it has infected a plant requires a lot of patience and continued care. Depending on the severity of scale and the cost of the plant it can be easier to just toss it. Trimming infested leaves and stems can help. If you can get your finger underneath the shell-like cover, you can usually pry the scale off of the plant. To treat scale, use a combination of neem oil and isopropyl alcohol. Apply neem oil to the whole plant once a week for the next 3-4 months. Make sure to apply it in the evening to avoid foliage burning. Use warm water and either castile or dish soap to act as an emulsifier with the neem oil concentrate. If your neem oil comes premixed do not worry about adding anything in. Concentrate: 2 cups warm water 3/4 tsp neem oil concentrate 2-3 drops of free & clear dish soap or castile soap Alcohol needs to be diluted into a spray before use on foliage. Spray the whole plant once a week for the next 3-4 months in addition to the neem oil. I would recommend using the alcohol and neem oil on different days e.g., Monday and Thursday. Alcohol spray: 1/2 cup isopropyl alcohol 70% 4 cups water Additionally, if you see any scale try using a cotton swab with alcohol on it to remove the insect. The earlier you can catch a scale outbreak among your plants the easier it will be to contain. I have personally dealt with scale on a large H. nummularioides and despite my best and constant efforts I was not able to salvage the plant. References:
Mahr, S. (n.d.). Scale insects. Wisconsin Horticulture. Retrieved February 19, 2022, from https://hort.extension.wisc.edu/articles/scale-insects/ Held, D. (2019, June 17). Controlling scale insects and mealybugs. Alabama Cooperative Extension System. Retrieved February 19, 2022, from https://www.aces.edu/blog/topics/lawn-garden/controlling-scale-insects-and-mealybugs/ Fungus gnats are mosquito-like flies that do not bite and are often mistaken for fruit flies. They are frequently found in the top 2-3 inches of soil. Gnats prefer a moist environment and feed on organic matter. Dyer, M. H. (2021). Adult fungus gnat. Gardening Know How. Retrieved February 13, 2022, from https://www.gardeningknowhow.com/plant-problems/pests/insects/fungus-gnats.htm. The problem with fungus gnats is even though they don't have a long lifespan one female gnat can lay up to 200 eggs. Once a fungus gnat problem arises, it does take some time to get rid of them. Typically, fungus gnats eat algae, decaying matter, and fungi. The larvae are known for eating plant roots. Additionally, gnats can easily spread plant diseases from one plant to another which can be problematic. Fungus Gnat Life Cycle. (2022). How to Get Rid of Fungus Gnats - Quickly & Permanently. Retrieved February 13, 2022, from https://worstroom.com/how-to-get-rid-of-fungus-gnats/. Luckily, fungus gnats are fairly easy to treat. There are many options on the market to control fungus gnats. I have personally tried Mosquito Bits, yellow sticky traps, hydrogen peroxide, sand, and bottom watering. The most effective method I have found is Ecological Labs Microbe Lift Mosquito Control. It is very cost effective, completely eliminated the infestation, and requires minimal effort. I mix in 2-3 drops per gallon of water to keep fungus gnats away. I found that Mosquito Bits are decently effective at treating for fungus gnats but not as great as the Ecological Labs Microbe Lift Mosquito Control. I would discourage sprinkling the bits directly into the soil as this leads to them turning moldy. The most ideal way I found to use Mosquito Bits is to make a tea. To make tea mix 4 tablespoons of Mosquito Bits into one gallon of water. Let this mixture sit for 30 minutes and then strain out the bits. Use this tea to water your plants as normal. Sticky traps are great for catching adult fungus gnats during an initial infestation. However, if you have pets be prepared for the sticky traps to at some point get stuck onto your pets’ fur especially if you have cats. If you do decide to try sticky traps make sure you buy the yellow ones because fungus gnats are attracted to the color yellow. Sticky traps are definitely not a long-term solution and over time they are not pleasing to look at. For the hydrogen peroxide method, you can mix 4 cup water to 1 cup hydrogen peroxide 3% and spray down the soil once a week. Sand is probably the messiest option and not the cheapest. The idea is to create a barrier so that the fungus gnats cannot get to the soil. 10/10 do not recommend. Bottom watering is when you don't water from the top down but instead set the plant into a saucer or sink filled with water and let it absorb from the bottom up through capillary movement. This method can help keep the top few inches of soil dry to discourage fungus gnats. Systemics containing imidacloprid are also a great way to kill fungus gnats. I personally use Bonide annual tree and shrub insect control (liquid imidacloprid). It also comes in granules. References:
Cransaw , W. S., & Cloyd, R. A. (2016, April 15). Fungus gnats as houseplant and indoor pests - 5.584. Retrieved February 13, 2022, from https://extension.colostate.edu/topic-areas/insects/fungus-gnats-as-houseplant-and-indoor-pests-5-584/ Buying plants in the winter can be a risky endeavor especially when temperatures start to drop. I am by no means an expert when it comes to cold damage but I think it's an important topic to address. Moreover, cold damage can also occur if your plants are too close to cold windows or if you have an unseasonably cold home. Tropical plants naturally require higher temperatures and greater humidity therefore making them more susceptible to freezing temperatures. Excessive cold can rupture plant cells and cause a lot of damage. Furthermore, cold damage does not just apply to tropical plants being exposed to below freezing temperature (32F) but also in the range of 32-50F. Some Hoyas in particular may be fine closer to 50F e.g; H. polyneura while others might start to decline at that same temperature. I think it's important to note that there is a difference between frost and freeze damage. Frost damage is when the plant cells freeze and form ice crystals which rupture the cell walls. Freeze damage on the other hand, occurs during continual temperatures 32F>. Freeze damage can hinder long term plant growth and can be less noticeable right away. Signs and Symptoms of potential cold damage:
Bunn, S. (2021). Hoya carnosa 'Wilbur Graves' with cold damage. Retrieved February 13, 2022, from https://www.facebook.com/groups/3103595163059302/search/?q=cold%20damage. Thigpen, T. (2022). Hoya heuschkeliana variegata with cold damage. Retrieved February 13, 2022, from https://www.facebook.com/groups/3103595163059302/search/?q=cold%20damage. It is still possible to buy plants in the fall and winter that arrive in great condition. To help mitigate cold damage there are steps you can take. First, be mindful of your local weather forecast when buying plants online. Second, if the shop you purchase from offers heat packs or winter insurance definitely get it. Third, purchase from sellers that you know will take great care in packaging your plant so that it does get to you in good condition. Lastly, if you are still worried about cold damage either hold off on buying plants online or request the seller to hold the plant for you for a short period of time when possible. References:
Reddick, L. (n.d.). Identification and Prevention of Frost or Freeze Damage. Retrieved February 13, 2022, from https://cals.arizona.edu/mohave/master_gardeners/kingman/articles/frostorfreeze.pdf Something I continue to struggle with 3 years into houseplants is watering frequency. Using different grow mediums have a major influence on watering schedules. Previously, I used a soil mix of pumice, Foxfarm ocean forest, and bark. Click here to be taken to the recipe. This mix dried out fairly quick in my environment and I could get away with watering weekly without having much of a problem. This mix in particular was great for my over watering tendencies. I experienced very minimal root rot. I tried a lighter airy mix consisting of coco coir croutons, charcoal, coco coir, worm castings, and pumice. Click here to be taken to the recipe. I found that I only had to water every 10-14 days with this mix. However, due to my watering tendencies I had a hard time waiting that long and eventually transitioned out of that mix due to root rot issues. After my soil experiences, I decided to go completely semi-hydroponic. Most of my collection is still in DIY pon. Click here to be taken to the recipe. I haven’t quite decided after 4+ months of using it if I love it. I think for anyone who tends to overwater, pon is probably not the best medium. My current watering routine involves using a reservoir and watering every 10-14 days depending on size of leaves. Small leaf Hoyas need more frequent watering because they can’t hold as much water in the leaves. I let the water sit for a day or two and then I dump out the reservoirs. I have experienced quite a bit of root rot using pon and switching up my watering habits to 10-14 days has definitely helped. I also recently bought “the perfect pot for semi-hydroponics” by Planty Queens. I have been using them for a few weeks and so far, I like them. I haven’t noticed root rot which was my main concern with the wick system. I have only had to refill the basin up once and I did let it completely dry for a week just to help prevent root rot. I have heard of people adding in a drop or two of hydrogen peroxide to the reservoir for root rot prevention but I have not personally tested that out. Additionally, I use LECA but not as a permanent grow medium. I find great success in using LECA for cuttings. I use a reservoir and keep it filled up to a certain point on a heat mat. Click here to read about LECA propagation. I have been meaning to try LECA as more of a long-term medium but haven’t done so yet. I have also been experimenting with transitioning from pon to plain coco coir. I figured since I do over water if I switch to coco coir it will dry out fairly fast and I can water more on a weekly basis. I would say 95% of the Hoyas I transferred took to the coir really well and are going strong. I did use a heat mat during the initial few weeks post transfer to promote root growth. If you find yourself overwatering your plants consider switch from a plastic nursery pot to a terracotta pot. Terracotta is moisture wicking and will help suck up some of the water. Regardless, watering is something highly variable with your environment and grow mediums. Click here if you need help with root rot.
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