Christmas cactus root rot

Cactus Problems: Why Is My Cactus Going Soft

Cacti are remarkably durable and low in maintenance. The succulents need little more than sun, well drained soil and rare moisture. The pests and problems common to the plant group are minimal and usually easy to surmount. Cactus problems may range from sucking pests, like whitefly, to common rots from bacteria or fungal disease. One of the telltale signs of a problem is a soft, mushy cactus.

Why is My Cactus Going Soft?

The arid gardener may ask, “Why is my cactus going soft?” Likely causes are disease, cultivation and improper site and ambient conditions.

Cacti generally have low moisture needs. They thrive in temperatures above 70 to 75 F. (21-24 C.) in sunny locations and require little supplemental nutrients. Potted plants need good drainage holes and a soil mix with plenty of grit. In-ground plants have similar requirements.

As with any plant, cacti can become diseased or damaged. A common problem is soft spots in the flesh of the plant. These may be discolored or corky around the spot and the center is mushy and wet. The reasons

for such spots may be disease or simply mechanical injury to the pads and stems of the cacti. Cactus rot issues must be dealt with quickly to prevent spread to the rest of the plant and serious loss of vigor, which may become permanent.

Cactus Problems with Fungal and Bacterial Diseases

Bacteria and fungus are introduced to the plant from openings in the flesh. The open areas may be from insect or animal activity, damage from inanimate objects or heavy weather, such as hail. The action of injury isn’t important, but the damage from fungal spores or bacteria is crucial.

Warm, moist conditions accelerate the production of fungi spores and increase bacterial production. Once the organism takes hold in your plant, you will see soft, mushy cactus. Symptoms to watch for include small sunken spots, discolored scabs, round soft areas surrounded by fruiting bodies, and black or other colored dots on the surface of the cacti skin. You may even notice some oozing of your cactus plants.

Treating Cactus Rot Issues

Cactus problems that have gotten into the root usually result in a slowly dying plant, while topical issues in the upper body can be treated easily. Most cacti respond well to excising the diseased tissue. Use a sharp sterile knife to dig out the damaged flesh and allow the hole to dry out. Don’t water overhead as the wound closes.

If the damage has infected the roots, there is very little you can do. You can try to repot the plant, removing diseased soil and replacing it with sterile soil. You should wash the roots off well before replanting in fresh potting medium.

A soft, mushy cactus can also be saved by taking cuttings and letting them root for a fresh new plant. Allow the cutting to callus over for a few days before you insert it into sand. Rooting the cutting may take several weeks. This method of propagation will produce a healthy cactus that is the same as the parent plant.

Christmas Cactus Diseases: Common Problems Affecting Christmas Cactus

Unlike typical desert cacti, Christmas cactus is native to the tropical rain forest. Although the climate is damp for much of the year, the roots dry quickly because the plants grow not in soil, but in decayed leaves in the branches of trees. Christmas cactus problems are usually caused by improper watering or poor drainage.

Christmas Cactus Fungal Issues

Rots, including basal stem rot and root rot, are the most common problems affecting Christmas cactus.

  • Stem rot – Basal stem rot, which generally develops in cool, damp soil, is easily recognized by the formation of a brown, water-soaked spot at the base of the stem. The lesions eventually travel up the stem of the plant. Unfortunately, basal stem rot is usually deadly because treatment involves cutting the diseased area from the base of the plant, which removes the supportive structure. The best recourse is to start a new plant with a healthy leaf.
  • Root rot – Similarly, plants with root rot are difficult to save. The disease, which causes the plants to wilt and eventually die, is identified by a wilted appearance and soggy, black or reddish brown roots. You may be able to save the plant if you catch the disease early. Remove the cactus from its pot. Rinse the roots to remove the fungus and trim rotten areas. Repot the plant in a pot filled with a potting mix formulated for cacti and succulents. Be sure the pot has a drainage hole.

Fungicides are often ineffective because specific pathogens are difficult to identify, and each pathogen requires a different fungicide. To prevent rot, water the plant thoroughly, but only when the potting soil feels slightly dry. Let the pot drain and don’t allow the plant to stand in water. Water sparingly during the winter, but never let the potting mix become bone dry.

Other Diseases of Christmas Cactus

Christmas cactus diseases also include botrytis blight and impatiens necrotic spot virus.

  • Botrytis blight – Suspect botrytis blight, also known as grey mold, if the blooms or stem are covered with silvery gray fungus. If you catch the disease early, removal of infected plant parts may save the plant. Improve ventilation and reduce humidity to prevent future outbreaks.
  • Necrotic spot virus – Plants with impatiens necrotic spot virus (INSV) display spotted, yellow or wilted leaves and stems. Use appropriate insect control, as the disease is usually transmitted by thrips. You may be able to save diseased plants by moving them into a clean container filled with fresh, pathogen-free potting mix.

Sad Looking Christmas Cactus

My wife has a Christmas cactus plant that she bought in Kansas years ago. It blooms and shoots in the same manner as a Christmas cactus, but the leaves are rounder and scalloped. We think it has root rot due to watering. It is limp, shriveled, and sad looking, but still has its color and flowers. Is there hope for this plant?

Sounds like you have an Easter cactus (Schlumbergera gaertneri ). Similar in appearance, this plant requires the same care as the Christmas and Thanksgiving cacti. These succulent plants are native to tropical areas. They are not as drought tolerant as the cacti of the southwest but they do not tolerate soggy soil. Too much or not enough water can cause the symptoms you describe. Keep flowering plants slightly moist. Once the plant is done blooming you can reduce watering frequency. This may also be a good time to repot the plant. Use a similar or slightly larger (if the plant was potbound) container with drainage holes. Remove any slimy roots and use a well drained potting mix to fill the container. Water non blooming plants thoroughly whenever the top few inches of soil is dry. Pour off the excess water that collects in the saucer to avoid root rot. Cacti and succulents prefer cool temperatures and dry soils when growth slows or stops over winter.

By Brian A. Krug|March 25, 2014

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Figure 1

Figure 1. The substrate on the left is comprised of small particles that will hold more water (represented by the blue rings), due to the greater surface area by volume and smaller spaces between each particle, as compared to the substrate on the right, comprised of large particles.

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Root rots like pythium, phytophthora and rhizoctonia are common diseases that attack young bedding plants in the spring and we often find ourselves treating prophylactically or curatively at some point during the growing season. These diseases have many sources, but plants that are stressed and over-watered are usually more prone to attack.

I recently took an informal poll of growers at a meeting to determine how many growers enjoy the task of “spot-watering” (checking each pot individually and watering according to that individual’s needs). Not surprisingly, no one confessed to liking the job.

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“An ounce of prevention is worth a pound of cure” is how the saying goes, and it couldn’t be truer when we consider our greenhouse crops. We often think about preventative strategies like good sanitation and scouting to prevent disease and insect problems. However, the substrate, and how you handle the substrate, is an often-overlooked preventative measure to avoid production and disease problems later in the season. In most cases when we think about disease control and substrates, we want to focus on the physical properties, specifically the pore space and the water-holding capacity of the substrate.

Choose The Right Substrate

Let’s first consider the selection of your substrate. Substrate manufacturers have a multitude of products to offer us; it is our job to select the appropriate substrate for the scenario we are growing in. If we take a closer look at the substrates available to us, we will find dramatic differences between them. The obvious difference is the components that are used to create the substrate. Peat and perlite are the standard components, but we also have vermiculite, coconut coir, compost, rice hulls and bark, just to name a few.

To complicate the issue, each one of these can come in different grades or sizes that will also influence the pore space and water holding capacity. Generally speaking, the larger particle sizes in your substrate will facilitate drainage; therefore the opposite is true, the smaller particle sizes will facilitate water-holding capacity.

We can see this in Figure 1. After irrigation, the water has drained from each of the substrates and only the water that is held on the surface of the particles is left (blue outlines on the particles). The substrate on the left has smaller particle size, and by volume has more water than the larger particles on the right.

How can we use this knowledge to our advantage? Take note of the season, the crop and your irrigation habits. Choose a substrate with better drainage in cooler seasons, for crops that do not tolerate wet conditions, or if you tend to run your crops on the wet side. Conversely, in warmer seasons, crops that require a lot of water or if you tend to run your crops on the dry side, you may choose to use a substrate that has better water-holding capacity.

Different Pot Sizes Drain At Different Rates

The particle size is not the only influence on how our substrates drain. The pots we use can actually have a dramatic effect on substrate drainage. Taller pots drain better than shorter pots.

You can see in Figure 2 the percent of air, water and solids in an identical substrate in different sizes of pots. This phenomenon has more to do with the height of the pot than the diameter. As the pot increases in height, the ability of the substrate within it to hold water against the force of gravity decreases. Therefore, the taller 6-in pot drains better than a 4-inch pot and a plug flat will drain even less, the same way a standard pot will drain better than an azalea pot of the same diameter.

Now you may be thinking about that plug flat that doesn’t drain as well as other taller pots and how often you need to water plug trays, especially as the seedling matures. The rate of drying is not due to drainage, but to evaporation and the water uptake of the plant via transpiration, coupled with the relatively low volume of substrate. So yes, the plug flat might dry out faster, but it isn’t due to the rate of drainage.

Avoid Nesting Pre-Filled Flats And Pots

Many growers prefer to fill flats and pots prior to use. After the containers are filled, they are palletized and stored until they are needed.

When filled containers are filled and stacked, we run the risk of compaction due to pots nesting within each other (Figure 3). When the substrate is compacted, we have decreased or even eliminated the amount of air space in the pot, and air space means drainage. When a grower uses these pots, they will stay wet longer than non-compacted pots and increase the risk of root rot diseases (Figure 4).

The problem is accentuated because the pots on the bottom of the pallet are compacted more than the pots at the top. Once the pots are distributed on the bench, there will be vast differences in drainage and therefore, when they will need to be irrigated again. So begins the endless cycle of spot watering (Figure 5). It is acceptable to pre-fill pots and to stack them, just be sure to offset them or place sheets of plywood between layers to avoid nesting.

Take these simple concepts and apply them to your operation and you will surely be rewarded with healthy plants, a crop with less root disease and fewer frustrations from spot watering.

Brian A. Krug is an Extension assistant professor at the University of New Hampshire Cooperative Extension. E-mail him at See all author stories here.

Root Rot Remedies

Root rot is a universal problem in commercial crops, yet our knowledge about it is fragmented. Understanding the root of the problem is at the foundation of effectively managing the disease. To be able to do that, you must learn about some of the microbiology that is running the show. Once you understand that, developing, integrating and optimizing treatments becomes easier, and you will be able to prevent root rot from developing in your plants.

To begin, let me introduce you to one of the main micro-organisms responsible root rot: Pythium spp. These fungi are widely spread around the globe and cause big problems in both indoor and outdoor gardens, whether you are growing in soil or hydroponically. Now we know who we are fighting, our mission is to analyze the pathogen to understand how it works so we can make its life unbearable.

What Causes Root Rot?

The Pythium spp. genus belongs to the family of Pythiaceae, which is in the oomycetes genus. Each species is able to produce zoospores (asexual spores that move) and oospores (thick-walled sexual spores) in infected plant roots and in the rhizosphere. These Pythium spp. are lethal. Why?

Well, they attack a wide range of host plants and they colonize frequently in soil, greenhouses, outdoor gardens and hydroponic systems—pretty much everywhere.

When the pythium’s zoospores encyst, they become immobilized. This makes the spores more resistant to extreme temperatures, desiccation and ionic environments. Oospores can survive for several months in fragments of dead roots, which may then be introduced and dispersed into gardens by infected transplants or reused media, polluted water, contaminated equipment and workers.

In The Annals of Applied Biology and Phytophatology Journal, researchers reported finding Pythium spp. oospores in the digestive tracts of larvae and adult fungus gnats and shore flies in North America. It is likely these insects help spread root rot in crops growing in warm and tropical climates.

During the infection process, mycelium (germinating oospores) form sporangia (zoospores), which encyst at the root surface to develop the germ tube that penetrates the root surface until the colony functions independently. Generally, the frequently penetrated areas are root tips, elongation zones and young root hairs, but most of all, root zones with increased root mucilage production.

Through a plant’s anatomy, we can link the root mucilage with the root apical meristem (RAM), a tissue that contains undifferentiated cells. These cells are capable of continued cellular division, which means RAM is required to provide new cells for root expansion and initiation of new organs, providing the basic structure of the plant’s body. If the root mucilage is colonized, the RAM is too.

Studies published in The Journal of Plant Pathology show the mucilage serves as a food base, enabling Pythium spp. to invade the roots, including old roots that zoospores normally do not infect. Under microscopic observations, the amount of mucilage was correlated with root browning, a necrosis reaction that develops in root tissues after they are infected and colonized by Pythium spp. and is associated with the accumulation of phenolic polymers.

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Pythium necrosis is induced by an elicitor, which has a high degree of similarity with necrosis-inducing elicitors of Phytophthora spp. and Fusarium oxysporum. It is important to mention that qualitative and quantitative changes in mucilage and other exudates from roots at various stages of crop development appear to affect root-zone microbes, including Pythium spp. and other micro-organisms, both beneficial and harmful.

The Symptoms of Root Rot

Besides problems with their roots, crops affected by root rot often show signs of stunted shoots, wilted leaves and a reduction in flowering and fruiting productivity. Plants experiencing severe root rot often appear to be healthy, even though growth is stunted and roots are decaying. In most scenarios, stunted growth may go unnoticed for a considerable amount of time because all plants in the cohort are similarly affected.

The Treatment

The factors that make plants vulnerable to root rot include a low concentration of dissolved oxygen in the nutrient solution and a lack of oxygen in the soil, constant warm temperatures, high humidity, damp soils, excessive amounts of phenolic compounds and dark environments. If Pythium spp. grows under these conditions, it is good practice to control these conditions to prevent and even correct the disease.

Beneficial micro-organisms are one of the most effective ways to prevent and treat root rot. Options for bringing in good micro-organisms into your root mucilage include using aerobic bacteria (produced in compost teas), efficient micro-organisms (EMs), lactobacillus, mycorrhizae and trichoderma.

The key is to apply these beneficial solutions when a plant is a seedling or at first transplant and to keep administering the treatment with the same micro-organism to build up the root zone’s microflora throughout the plant’s lifetime. Just remember that using chemical fertilizers, chemical additives and chlorinated water can kill your happy micro-organism family.

Microbes have also been used to digest phenolic compounds and raise oxygen levels. A good choice is Bokashi, which usually has tons of actinomycetes that boost oxygen levels in soil systems and even in hydroponic systems, which typically have a low microbial diversity.

The most effective EM you can get is a local EM, which can be obtained from your local forest. To get it, fill a dish with wet rice and place it in a dark damp place in the forest for 2-4 weeks. Spring and fall are the two best times to do this. The longer you leave it, the more fungal the compound will be, and the shorter you leave it, the more bacteria-rich it will be. This is simply because bacteria reproduces faster than fungus grows.

The Growroom Set-up

When it comes to winning the battle against root rot, there are some things to consider when setting up your growroom. For instance, while some growers produce their own transplants, many people end up buying them from other growers. In some cases, the plant stock can be contaminated, and since many infected transplants are usually symptomless when ready for shipping to growers, the supplier might not even be aware of the problem. It is important to obtain plants from reputable growers—I can’t stress this enough.

Some growers reuse contaminated soil or rooting media such as slabs of stonewool or coconut fiber without sterilization, allowing for the carryover of various pathogens to the subsequent crop. In hydroponics, pipes, tubing, tanks and other plumbing components can be contaminated even when the systems are treated with disinfectants. Nutrient solution circulation is one of the primary ways Pythium spp. are dispersed in hydroponic crops.

Reports of severe epidemics are more frequent for crops grown in systems in which the nutrient solution is circulated amongst hundreds of plants before returning to the mixing tank, as opposed to highly compartmentalized systems such as stonewool slabs, where only few plants share a common root zone. While the buildup of root microflora is important in the fight against root rot, proper sanitation practices and using new materials and rooting media will help prevent the carryover of unwanted pathogens.

Outdoors

In warm, rainy outdoor climates, plants are highly susceptible to Pythium spp., Phytophtora spp. and Fusarium oxysporum. When the first rain falls after long periods of hot, dry weather, the rain will flood the soil, it will drain poorly and roots will suffocate. These dead roots produce phenolic compounds, which are probable carriers of oospores. It is important to use preventative measures in these types of growing conditions, such as mulching your soil to prevent it from becoming too hot.

When all is said and done, preventing and controlling root rot is not as difficult as it may seem, as long as you take these small steps to prevent the disease. Not only will your plants’ roots be disease-free, but using helpful bacteria and micro-organisms will allow your plants to be healthier and produce more. Just remember to use new materials when transplanting, be aware of the environmental conditions in which you are growing and adjust accordingly, and supply the right amount of helpful micro-organisms to keep your plants happy.

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Christmas Cactus

Christmas cactus, also known as the Orchid Cactus, is a great gift idea on Christmas eve especially when in full bloom. The Christmas cactus is a popular, winter-flowering houseplant native to Brazil. The pendulous stems of the Christmas cactus makes it a great choice for hanging baskets.

Kingdom Plantae Division Magnoliophyta Class Magnoliopsida Order Caryophyllales Family Cactaceae Present poinsettias as a gift to your dear ones and you will be able to remind him/her of the myth associated with the flower. He/she will be grateful after receiving this gift from you. To get fresh and beautiful flowers, shop now.

What is a Cactus?

A cactus (plural, cacti) is a type of succulent plant belonging to the dicotyledonous flowering plant family, Cactaceae. The Cactaceae has around 90 genera and some 1,500 to 1,800 species. Cacti are well-known natives of the Americas, mostly found in desert areas. Some are also rainforest epiphytes, growing on tree branches where, despite the high rainfall, water drains off quickly so that “dry” conditions prevail much of the time.

Like other succulents, cacti are well-adapted to life with little precipitation. The leaves have evolved into spines, which in addition to allowing less water to evaporate than regular leaves, defend the cactus against water-seeking animals. Photosynthesis is carried out by enlarged stems, which also store water. Unlike many other succulents, the stem is the only part of a true cactus where this takes place.

Facts about Christmas Cactus

  • Cacti are believed to have evolved in the last 30 to 40 million years ago.
  • Like many tropical cacti, Christmas Cactus is also an epiphyte.
  • The flowers are available in a wide variety of colors including red, purple, orange, pink, fuschia, cream, etc.
  • The Christmas cactus is a member of a group sold as holiday cacti that also include the Thanksgiving cactus and the Easter cactus.
  • The green, flattened, leaf-like structures that make up the majority of a Christmas Cactus are actually modified stem segments called cladodes. In most cacti, the leaves have been modified into spines which have many different functions for the plant. In the Christmas Cactus, the leaves and the spines are absent.
  • Various plant species require cues from the environment to regulate the timing of certain events, like flowering. This mechanism called photoperiodism occurs when plants initiate flowering or other activities in response to relative lengths of daylight and darkness.

Popular Holiday Cacti

The three common flowering cacti are called holiday cacti. The three types of holiday cacti are-

Cactus Scientific Name Description
Christmas Cactus Schlumbergera bridgessii The Christmas Cactus has pointed lobed leaves and is given from Thanksgiving to Christmas. These are also called True cacti.
Thanksgiving Cactus Schlumbergera truncatus These cacti are also called Crab or Yoke Cacti. They are available from early fall and all through Christmas.
Easter Cactus Rhipsalidopsis gaertnerii These cacti flowers have wider rounded leaves and are given from Christmas to Easter.

The stems of the Christmas Cactus consists of small cushiony sections called “areoles” which identify them as true cacti. On other cacti, spines and true leaves arise from the areoles. The flowers on the holiday cacti are formed on the tips of the segments.

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Growing a Christmas Cactus

  • The Christmas Cactus is easily propagated by taking short Y-shaped cuttings of the stem tips.
  • Remove a single segment and plant a quarter of its length deep in a pot filled with slightly sandy soil.
  • Place the pot in a well-lit area (but not under direct sunlight) and keep the soil moist.
  • The cutting should begin showing signs of growth after two or three weeks.
  • To root cuttings for new plants, cut back shoots from the tips. Cut at the second joint of each tip.
  • Place cuttings in a moist peat and perlite, or peat and sand mixture. Water sparingly at first to prevent rotting of cuttings.
  • After two or three weeks, water as you would do to any other cutting.
  • When cuttings are rooted, pot them in a very loose mixture of good potting soil.
  • While the Christmas Cactus can adapt to low light, more abundant blooms are produced on plants that have been exposed to high light intensity.
  • Keep your plants in a sunny location indoors or in semi-shady location. Too much direct sunlight can burn the leaves.
  • The ideal soil for Christmas Cactus is composed of equal parts of garden loam, leaf mold and clean coarse sand (not sand from the seashore).
  • After the plant completes blooming, let it rest by withholding water for six weeks.
  • When new growth appears, re-pot and top-dress with fresh soil. Resume watering to keep soil fairly moist.
  • As tender growth appears in spring, apply a weak solution of liquid houseplant fertilizer at 2 to 3 weeks.

Caring for a Cactus plant:-

  • Do not let the plant dry out. Water when the top half of the soil feels dry to the touch.
  • Be careful not to over water which can cause buds to drop.
  • To add more humidity to a dry atmosphere, place the pot on a tray of pebbles and keep the pebbles moist.
  • A Christmas Cactus needs a bright location out of direct sunlight.
  • Apply a mild houseplant fertilizer solution every other week.

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