Home growers and gardeners tend to be quick to learn one of the most uncomfortable truths about pests: tiny bugs are likely to be the biggest nuisance and to cause the quickest destruction – and spider mites, in particular, seem set on proving this!
These annoying little arachnids can quickly take over any garden or potted plant, especially if your ecosystem has been messed around with chemical insecticides. They are surprisingly resilient and quick to reproduce, to the point that rabbits could learn a thing or two from them!
The key when dealing with spider mites is to act quickly and decisively. But since the wrong kind of strong approach can cause almost as much damage to plants as the pest itself, my philosophy is always the same: know your enemy first. If you need to learn how to get rid of spider mites, then the following guide is for you.
- Quick Facts on Spider Mites
- Where do Spider Mites Come From?
- What does a Spider Mite Infestation Look Like?
- Types of Spider Mites
- From Birth to Destruction: The Life Cycle of Spider Mites
- Damage and Symptoms of Spider Mites
- Spider Mite Control
- Pests & Diseases affecting chilli peppers
- What’s Bugging My Peppers?
Aphid control in peppers
- The life cycle of an aphid
- Damage caused by aphids
- The chilli plant as a house plant
- Aphids On Pepper Plants
Quick Facts on Spider Mites
|Origin||Originally from Eurasia, but now they can be found across all tropical and temperate regions|
|Common Names||Spider mite, Red spider, Red spider mite, Two-spotted spider mite, Broad mite|
|Scientific Names||The most common ones are Tetranychus urticae and Panoychus ulmi, but there are hundreds of species, subspecies, and regional variants.|
|Identification||Extremely small arachnids, which often appear as tiny reddish or greenish spots to the naked eye. Adults grow only up to 0.4 mm long.|
|Favorite Plant Hosts||Roses, Potatoes, Tomatoes, Peppers, Eggplants, most beans, Chickpeas, Cherries, Apples, Stone fruits (peaches and plums), Clovers, Various Grasses, Hemp, most annual flowers|
|Remedies||Neem oil, Miticide blends (Bug Blaster, NukeEm, horticultural oil), Foggers, Predatory bugs (ladybugs, minute pirate bugs, big-eyed bugs)|
Where do Spider Mites Come From?
A long time ago, spider mites were only a problem in Eurasia – although it’s hard to say which side of it. At this point, they’re found across the world. If you live somewhere with a cold winter, at least you will only have to worry about potential infestations during half the year.
What does a Spider Mite Infestation Look Like?
Spider mites themselves are too small to be seen by the naked eye unlike other larger pests like squash bugs, June bugs. In all their six-legged glory – at most, you will be able to recognize greenish or red spots if you look at a plant closely. Their favorite place to hide is under the leaves.
Different species of spider mites have different colors, and some of them even have stripes, but you’d need a microscope to see that much detail.
The initial stages of a spider mite infestation can be recognized as small, dark brown or “burnt” spots on the surface of the leaves. A good way of identifying the pest at this stage is to wipe these little burnt spots with a soft tissue. If it’s mites, you should be able to see little streaks of mite blood.
Afterward, the eggs appear. These are small, spherical, and transparent.
To protect their eggs, spider mites produce a dense, very fine, sticky web that can quickly cover the entire plant. This will prevent your plant from getting enough sunlight and from transpiring or breathing properly. You don’t want to wait until the infection reaches this stage though.
Types of Spider Mites
As I mentioned before, there are literally hundreds of different species of spider mites. I will now focus on the four big subtypes that are most common across North America and Europe.
Personally, I have always found that these tend to look pinkish rather than a proper red. This subspecies is particularly prolific, and a colony can completely cover an indoor plant in a couple of days. As they’re so small, they are usually only visible after an entire leaf (or several) has been completely covered by a haze of tiny dark pink spots.
Despite their name, these are actually smaller than red mites: where a red mite can grow to up to 0.4 mm, broad mites usually stay within the 0.1-0.2 mm range. However, broad mites can be extra virulent and deadly to your plant.
This is because female mites they secrete a toxic growth hormone into the plant that will literally poison it. This is in addition to all the nutrients they are already robbing your orchids and roses from.
Their tell-tale sign is that any infected leaves will start curving upwards near the edges as if they were wilting. After this happens, it usually takes less than five days for that leaf to turn dark-bronze and to dry off completely.
Hemp russet mites
The best thing to say about hemp russet mites is that they leave no webbing. That is the only quality they have, unfortunately – in every other sense, they’re awful.
Hemp russet mites are the smallest of the common mites, so they can really only be seen with a microscope. They also have only two legs, rather than the six that broad or red mites sport. As they are relatively slow climbers, they will usually crawl their way up into the plant – leaving a trail of brown, burnt damage behind.
These are broad mite’s 8-legged, fast-breeding cousins. As a bonus nuisance, they have tiny claws that they use to climb over stems and leaves. Out of all common mites, they are also the ones that are fondest of humidity. This makes them particularly dangerous for greenhouses.
Although they will colonize almost any plant they meet, they tend to prefer low-lying flowering plants with delicate or soft leaves, as they are the easiest to perforate with their claws. African violets tend to be a favorite.
From Birth to Destruction: The Life Cycle of Spider Mites
Thanks to their wide variety of subspecies and types, the life cycle of spider mites will also be very varied. Their total life span will range from five days to a full month, and the speed in which they spawn also varies. However, it never varies to be too fast for comfort (University of Florida).
Spider mites come in both female and male versions. Female mite eggs require fertilization, while males do not. After a female lays her eggs, these will take between one to three days to hatch.
The tiny larvae will then go through two separate stages (protonymphal stage and deutonymphal stage) before becoming a sexually-mature adult. Once they reach this stage, females will immediately begin seeking an available male to fertilize their eggs – although they always make sure they leave some unfertilized, to ensure there are future males to come. Provided temperatures stay above 80°F, females will get themselves fertilized and hatch more eggs continuously – and then proceed to cover its nests with the dreaded webbing that signs a late-stage infestation. Although they only live around a month in average, each female can produce hundreds of eggs during her life.
If temperatures drop below 70° F, fertilized females will enter a state of diapause or dormancy, and wait until the weather turns warm again.
Damage and Symptoms of Spider Mites
There are two main ways in which spider mites will harm your plants: by feeding and by the webbing they use to protect their eggs (American Orchid Society).
Spider mites suck dry the nutrients and chlorophyll directly from your plant’s leaves. As they are so small, they usually do this cell by cell. This is why the initial signs of their feeding are usually just tiny brown or dry spots underneath the leaf.
As hard to notice as they are at first, once they begin reproducing and you get a small army on your windowsill, they can affect an entire leaf within a day. Leaves will then change color and turn dark yellow or brown; the edges will start curling up, and eventually dry off.
Spider Mites Web
As I mentioned in the Life Cycle section, most species of spider mites are infamous for the spider-like web they use to hide and protect their eggs. Females will usually start creating this web immediately after laying their eggs. This web will then prevent water and light from reaching the plant, hindering photosynthesis – which is essential for the plant’s survival.
Depending on the type of plants you are growing, the damage can be simply aesthetically unpleasant, or it may kill off the plant entirely. Roses and African violets, which are notoriously frail, are particularly susceptible to this.
When it comes to food crops, they can cause your tomatoes or peppers to receive sunburn damage, or to become stunted – as the whole plant will be suffering if photosynthesis becomes impossible. If you are growing beans, peas, or anything that comes in a pod, you may be looking at losing the entire harvest: spider mites will feed off the pods themselves.
Spider Mite Control
Just like with any other pest, I usually advocate a prevention-first approach. Once they have invaded your field, there are chemical, biological, and physical methods you can use to banish them.
Your first line of defense should be quarantined. Always make sure that any new cutting or gifted plant you bring to your home or greenhouse is completely clean. Because they’re so tiny and hard to spot, this is particularly important when it comes to preventing spider mites: even if just two or three manage to get inside your greenhouse unnoticed, they can become 500 hundred in five days, and 500 x 500 in ten days.
For the plants that are already in your home, try any of the following:
Control their environment: spider mites like hot and dry spaces. Keep your plants well hydrated, shade the leaves from direct sunlight, and spray them with some water to ensure they don’t get the chance to become too comfy.
Dust them off frequently: This will double as a chance to both prevent and detect a potential pest before it gets out of hand. Pay special attention to the hidden surfaces underneath each leaf. Remove and examine any dust on them at least once a week.
Rinse and wipe any suspicious leaves: gently, grab a moist cloth and wipe off each leaf from your rose bushes. This should be done every couple of weeks, throughout the summer.
Get bug allies: Get a few ladybugs to help you protect your ornamental plants. They’re pretty on their own, they are harmless and silent – and they will keep their living space free of myriads of other pests (Cedar Circle Farm).
Fighting Spider Mites – Pest Control Tactics
Getting rid of spider mites once they have appeared is no easy task. For those of you who are trying to strike the right balance between “decisive” and “safe for my family greenhouse,” try the following:
Isolate: After detecting an infected plant, immediately remove it somewhere far away from its peers. This is easier for indoor potted plants, naturally, but it still ought to be attempted in the garden
Mite-killing products: Make sure you read all labels properly to ensure they are safe, effective, and actually work against mites. Keep in mind that spider mites are arachnids, not insects so that insecticides will be laughed off as a perfume by most spider mite colonies.
Bug bombs: If the sick plant is in a pot and you can easily move it to its own room, where it won’t be within reach of other plants, pets, or people, try using a sulfur-based spray or “bug bomb.”
Neem oil: Personally, this is one of my favorite horticultural oils, as it works against a large variety of pests. It is quite effective against spider mites, but you should ensure any plants treated with neem oil are kept away from children or pets.
Clean off the plant and environs: Wash each leaf carefully with a gentle soap and wipe it clean. Also, replace any mulch or hummus that may be surrounding the plant – spider mites love to hide in there!
Get them eaten off: Biological controls are a great, family friendly way to both prevent and exterminate spider mites without accidentally harming the family dog. Some of the most popular species used against spider mites can be bought in greenhouses or specialized stores, and they include:
Ladybugs: Pretty and fond of both mites and aphids – a single ladybug will eat up to 5000 a day.
Lacewings: Not to be confused with lacebugs, which are actually a pest of its own. They will eat most larvae and caterpillars, in addition to mites.
Minute pirate bugs: A great live-and-let-live friend for your outdoor plants, they can become a bit of an annoyance indoors (The Canadian Organic Grower).
Spider mite destroyers: Also known as Stethorus punctillum, these little tanks are akin to bringing the heavy, specialized artillery. They will target spider mites specifically, and can eat hundreds of both adults and larvae per day (Cornell University).
Predatory thrips: This tiny black and white insects will feed off your garden’s pest – although unfortunately they are often mistaken for plant-sucking species (University of Minnesota).
Big-eyed bugs: Despite being very similar to chinch bugs, true big-eyed bugs are actually harmless and very helpful to get rid of spider mite larvae.
Spider mites are known to be the bane of many home horticulturists and gardeners. Tiny and quick, they can wreak havoc across an entire rose garden in a matter of days. Look out for their signature brown spots before the webbing begins its own damage – and don’t hesitate to experiment with the many beneficial bugs that can make a meal out of them.
Pests & Diseases affecting chilli peppers
So, you’ve bought (or saved) your seeds, carefully planted them and provided the optimum growing conditions. However danger lurks in every corner of the garden with a whole host of beastly pests and diseases ready to indiscriminately strike down your plants at a moments notice.
In general there are two types of factors which can bring death and destruction to your beloved chile plants – living (biotic) and nonliving (abiotic) agents. Living agents incude insects, bacteria, fungi and viruses. Nonliving agents include extremes of temperature, excess moisture, poor light, insufficient nutrients, poor soil pH and air pollutants.
This chilemans guide aims to provide an overview of some of the more common living agents that can infect your Chile plants to help you identify ‘the enemy’ and provide you with some ammunition to fight the problem. After all thechileman wants your plants to have a long and healthy life and produce a bountiful harvest of lovely chiles.
Know Your Enemy!
Unfortunately there are a whole host of pests & diseases that can infect Chile pepper plants. Thankfully, only a few are common in the UK with most more of a problem in hotter climates such as the Caribbean and Americas. Although most insects are more of an irritation than a terminal problem causing only localised damage, it is the diseases that they can carry which can do the real damage.
A study by Green, S. K. and Kim, J. S (1991), found that more than half of known viruses are transmitted by aphids (greenfly). Thrips, mites, whiteflies, beetles and nematodes transmit others. Some of the more serious problems such as Bacterial Leaf Rot and Tobacco Mosaic Virus (TMV) are transmitted by direct contact with infected plants, soil or garden tools with others transmitted through mechanisms not yet understood.
Diseased plants can exhibit a variety of symptoms, making diagnosis extremely difficult. Common symptoms include abnormal leaf growth, colour distortion, stunted growth, shrivelled plants and damaged pods. Although pests & diseases can cause considerable yield losses or bring death to your plants, none are believed to directly affect human health.
Prevention is better than the cure
As a general rule, most pests and diseases cannot be completey eradicated, but they can be managed and controlled to minimise the ‘collateral’ damage. Once a problem has taken hold it is often very difficult to control.
To manage potential problems, early identification, correct diagonsis and the swift implementation of preventitive methods should allow you to get on top of most problems before serious damage if inflicted.
However, for the sake of the environment before automatically reaching for the nearest bottle of poison, there are several much friendlier and easy organic strategies which can be deployed, particularly for controling insects. Unfortunately, the more serious viral & fungal infestations may require Chemical Warfare to be deployed. However, always read the instructions on the bottle carefully and take precautions when using chemical agents.
Organic Strategies for Managing Pests
1. Learn to tolerate some damage: Most healthy Chile plants can tolerate some damage without suffering serious long-term problems or yield reduction. Munched leaves/ damage pods can easily be removed to maintain the attractive appearance of your plant.
2. Introduce the ‘Good guys’: Aphids feeding in the spring can alarm many Chile growers. Introducing natural predators such as Ladybirds, Parasitic wasps and Lacewings will help clean up most local infestations in a month or so.
3. Hand pick/Hunt down: Hunting down snails and slugs and ‘disposing of them’ can be a highly satisfying exercise particularly if the little blighters have already struck your prized plants. Night time ‘slug hunts’ during wet weather can be particularly productive.
4. The Water Hose: A strong water hose will temporarily dislodge flies, aphids and other pests from mature plants. However be careful not to saturate or damage your plants and avoid this using method on young seedlings.
5. Remove diseased plants or plant parts: Simply removing and disposing of badly damaged plants can help reduce the problem and prevent is spreading to adjacent plants.
6. Crop Rotation: This is particularly important strategy for tackling soil borne pathogens such as Verticillium Wilt and root rot.
7. Grow pest resistant & pest tolerant plants: Many hybridised varieties, particularly some of the newer sweet pepper varieties have been developed to give specific resistance to diseases such as Tobacco Mosaic Virus (TMV) and Bacterial Leaf Spot.
8. Innoculate: When growing in pots it is likely that sterilized soil has been used. Sterile soil is ripe for colinisation by many forms of bacteria, fungi, & insects. It is quite likely that the first colinization will not be beneficial. However, just as you can buy yogurts containing beneficial bacteria from the supermarket, you can also buy beneficial bacteria for your soil (though it is a little bit more difficult to get hold of). Beneficial Mycorhizzal fungi is also available, and is starting to become popular in many on-line shops. It may also be useful, depending upon the scope of your growing conditions, to introduce beneficial soil dwelling predatory insects. Introducing your own symbiotic bacteria, fungi, and insects limits the likelihood of colonisation by parasitic forms. In addition to aiding growth of the chile plant, & providing tolerance to environmental stresses, many forms of bacteria and Mycorhizzal fungi are also thought to innoculate the chile plant from diseases and viruses. In addition, they are helpful at reducing the conditions that make these diseases and viruses possible.
What’s the Problem? – A Quick Reference Guide
Unless you are an expert taxonomist or have easy access to a laboratory, the correct diagnosis of the problem is probably the most difficult (and critical) factor in your battle with the enemy as a whole host of problems can display similar very symptoms. The following guide will hopeful help you narrow down the problem.
– see the sections on Aphids, Whitefly, Nematodes and Verticillium Wilt
– could also be caused by a Nitrogen or Magnesium deficiency, mineral deficiency, or excessive watering
– see Bacterial Leaf Spot and Phytopthora blight
– could also be caused by excessive nitrogen.
– see Aphids, Thrips, Spider mites and Viruses
– see slugs & snails and flea beetles
– see sunscald
– could be caused by Chemical or fertiliser burns
– see Bacterial Leaf Spot, Cercospora Leaf Spot Powdery Mildew, Phytopthora blight and viruses
– could also be caused by chemical injury
– see Bacterial Leaf Spot and Phytopthora blight
– could also be caused by insufficient watering
– see Verticilllium wilt, Bacterial Wilt & Phytopthora blight
– could also be caused by too little/too much watering
Plants Falling Over
– could be caused by waterlogged soil, insufficient plant support or poorly develop roots
– likely to be caused by inadequate light, poor soil, low temperatures. Note some Chile species particularly the Chinese are notoriously slow growing
– see slugs & snails and pepper maggots
– Birds and animals are also partial to the occasional chile pod (animals tend to avoid all but the mildest chile pods – though they might take a test nibble).
– see Anthracnose, Bacterial leaf spot, Blossom End Rot, Phytopthora blight, Grey Mold and thrips
– could also be caused by sunscald or nutrient deficiencies
– see Thrips, Spider mites and viruses. Poor Pollination can also cause this problem
– see Bacterial Soft Rot and Grey mold
Failure to Ripen
– insufficient ripening time likely to be the problem
The insects most likely to ‘enjoy’ your chile plants are slugs & snails, aphids (greenfly/blackfly), pepper maggots,whitefly and nematodes. Flea beetles, cutworms, hornworms, thrips, spider mites and leafminers are less common. To control insect problems, regular inspection is again the key to success.
Slugs & Snails are probably the number 1 enemy of gardeners, these little devils can quite happily turn one of your prize specimens into a swiss cheese practically over night before sliding back to there hideaways, leaving you to wonder what happened. Thankfully, most slugs and snails leave behind one piece of incriminating evidence which helps to both diagnose the problem and track them down, a trail of slime! Slugs are hermaphrodites (they can mate with themselves) and can produce dozens of eggs several times a year. The egg clusters look like little piles of whitish jelly and hatch anywhere from 10 days 28 days. ‘Dispose’ of any slugs and eggs wherever you find them.
Regular Slug hunts are the best course of action. Container gardening, the use of Copper tape/matting (placed around the plant) and even garlic oil has been used by gardeners with some success.
Aphids (Greenfly/BlackFly) are one of the commonest and most annoying all garden insects. They are particularly attracted to young tender shoots, sucking your plants dry of sap causing shoots and leaves to become distorted. Plants grown indoors and away from natural garden predators can be particularly prone to infestations. Image © Virtualpepper
Small infestations are relatively easy to control. One method is to introduce natural predators to do the job for you. A second is to attract them away from your like darlings by planting Marigolds (tagetes and calendula) close by. Marigolds are a feeding favourite of the aphids and the theory goes that they will be much more interested in the Marigolds than your Chile plants.
Other friendly ways of controlling aphids include rubbing them off with your fingers or spraying them with a very diluted soap solution, about one teaspoon of fairy Liquid pure soap (as near to 100% fatty acids as you can get – avoid antibacterial, perfumed, & detergent based soaps) to a couple of litres of water. More severe infestations are more troublesome and it may be better to isolate the plants to prevent the problem spreading to your other plants. Unfortunately, spraying severely infested plants will provide only temporary relief and may simply just shift the aphids from one plant to another.
Flea beetles are about 2mm long, shiny in appearance with enlarged hind legs which enable them to jump. Adult flea beetles feed on the undersides of young leaves leaving small pits or irregularly shaped holes. Larvae live primarily in the soil and feed on roots, but cause little damage.
Ensure rapid germination and development of seedlings so that they grow through this vulnerable stage quickly. Flea beetles feed at the height of the day, and they don’t like to get wet. Giving them a lunchtime shower can reduce the problem.
Pepper Maggots are whitish yellow, pointed at the head end and 0.5in longwhen fully grown. The maggots feed on the core inside of the pods which causes damaged peppers to turn red prematurely and rot.
Check pods for small puncture holes and destroy and infected pods. Rotting pods will attract other flies if left on the plant.
Root Knot Nematodes are microscopic, eel-like roundworms that live in the soil and feed on roots. Root damage reduces the plants ability to take up water and vital nutrients. Symptoms vary with plant age and the severity of the infestation, but include wilting, nonproductive plants and development of characteristic knots on the plant’s roots which can vary in size from smaller than a pinhead to larger than a pea. The problem can be particularly severe in sandy soils.
Crop rotation and adding organic matter to sandy soils can help reduce the impact of nematodes. The best method of control is to plant resistant varieties (often indicated by an N on the seed packet) like California Wonder & Charleston Belle.
Spider Mites can be a serious problem particularly during periods of hot, dry weather. They feed on the underside of leaves and to the naked eye, look like moving dots. When infestation is high, the leaves will have webs on them; if uncontrolled, these mites can kill a plant. Infected leaves often curl downwards and leaves are speckled in appearance, as though covered with hundreds or thousands of pale yellow dots. A simple technique for identifying mites is to tap an infected leaf over a piece of white paper. Wait a few seconds and watch for movement.
Red spider mites breed in hot and dry places. If you can increase the humidity around the plant you decrease the pest’s reproduction rate. Dampen down infected areas. For house plants a short holiday somewhere cooler and more humid (the bathroom?) may help get rid of the infestation.
Thrips are numerous in species and all are extremely small. They are very slender and may be white, yellow, brown or black. Affected leaves are often distorted and curl upward. The lower surface of the leaves can develop a silvery sheen that later turns bronze. Damage on pods appears as brown or silver areas near the calyx.
Thrips do not usually need to be controlled as predatory mites insects will normally do the job for you.
Whiteflies are tiny insects (1.5mm long) with broad wings that fly from the plant when disturbed. They suck plant juices from the leaves, causing them to shrivel, turn yellow and drop. Whiteflies also secrete honeydew which can cause foliage to become sticky and coated with a black sooty mold.
Whitefly control is difficult, since only the last (flying) stage of the whitefly lifecycle is vunerable to spraying. Whitefly control is difficult as they have very fast lifecycles. To eliminate this pest frequent spraying is necessary – at least once a week, and for many weeks/months. Good cultural practices, such as removing infected plants, pruning the top new growth, and/or using a mild diluted (fatty acid based) soap solution are possible controls. Perseverance is neededare the best controls.
Bacterial & Fungal Diseases
Anthracnose is caused by the fungi Colletotrichum piperatum and C.capsici and is promoted by warm temperatures, high moisture and poor circulation among the plants. Both sweet and hot peppers varieties are susceptible to this disorder. Although the disease does not seriously affect vegetative growth, it can seriously damage pods. Symptoms appear on both ripe and unripe pods and are characterised by sunken, circular spots that can grow up to 1in in diameter. In moist conditions, pink or yellow spore masses may appear.
Crop rotation and the use of disease-free seed. If the disorder is severe, a fungicide may be needed.
Bacterial Leaf Spot is caused by theseed borne bacterium Xanthomonas campestris pv vesicatoria which also causes bacterial spot in tomatoes and is one of the most serious bacterial disease affecting chiles. The principle sources are infected seed and transplants. Moist conditions encourage disease development.
This disease first appears as small water soaked areas that enlarge upto a quarter inch in diameter. The disease spots have black centres and yellow halos. The spots are depressed on the upper leaf surface, whereas on the lower surface the spots are raised and scab like. Severely spotted leaves will eventually turn yellow and drop off, leaving pods susceptable to sunscald.
Crop rotation and the use of disease-free seed. The use of copper-based fungicides can have some success although excessive use may retard growth and damage plants
Bacterial Soft Rot is caused by bacterium Erwinia carotovora pv carotovora and affects Chile pods. The internal tissue softens before eventually turning into a watery mass with a foul smell. This problem is worst in wet weather because the bacteria are splashed from the ground and onto the fruit. It can also be started by insect injury.
Keep plants off the ground (on greenhouse staging) and controlling insects can help reduce the threat of this disorder.
Bacterial Wilt is caused by the bacterium Pseudomonas solanacearum. The first symptoms start with the wilting of the leaves. After a few days, a permanent wilt of the entire plant results, with no leaf yellowing. You can test for this bacteria by cutting the roots and lower stems; look for milky streams of bacteria when they are suspended in water.
The best control is to plant clean seed and transplants and to remove diseased plants.
Cercospora Leaf Spot (Frog Eye) is caused by the fungi Cercospora capsici and is worst under extended warm, wet conditions. This disease in characterised by small brown circular leaf lesions that have a watery appearance. Excessive leaf drop may occur in common infestations.
Clean seed and crop rotation are the best preventative measures against this disease. Good airflow around plants in sheltered areas (greenhouse’s) will also help minimise this problem. Fungicides are probably the best solution if the problem is extensive.
Damping-off is caused by poor seed quality, improper planting depth, high salt concentrations, a wet seed beds or severe nutrient deficiencies. Several fungi such as Pythium, Rhizoctonia and Fusarium are associated with this problem. Seedlings fail to emerge (pre-emergence damping-off), small seedlings collapse (post-emergence damping-off), or seedlings are stunted (root rot and collar rot).
To control this problem plant only high-quality seed or vigorous transplants and avoid soil that is poorly drained. Good ventilation reduces surface moisture, and therefore the likelihood of damping off. The use of a fungicide, such as a copper based fungicide, or even just watering with chamomile tea (provides a mild fungicide at normal strength), can reduce the likelihood of damping off further.
Grey Mold is a relatively common problem and is caused by the fungus Botrytis cinerea. Symptoms include a sudden collapse of succulent tissues, such as young leaves, stems, and flowers. Grey powdery spore masses occur on the surface of dead plant tissues.
High humidity favours the disease. Ensuring your plants have good air circulation will helps reduce this problem. A fungicide is probably the best bet if the mold is severe.
Phytophthora Blight (Chile Wilt) is caused by a water borne fugus Phytophthora capsici and is generally observed in wet waterlogged areas. The fungus can invades all plant parts causing at least three separate syndromes: leaf blight, fruit rot, and root rot. It is promoted by warm, wet weather. Plants suffering from this condition often wilt and die, leaving brown stalks and leaves and small, poor-quality fruits. If the fungus enters the roots, the game is unfortunately over as the plants cannot obtain enough water (due to root rot), suddenly wilt, and eventually die. Symptoms of the less serve leaf blight include brown or black spots that may kill a localised portion of the plant. Affected areas are often bordered with a white mold.
Avoid excess watering and poorly drained soil. Fungicides can be used to treat leaf blight and fruit rot. Root rot is usually terminal.
Powdery Mildew is cause by the fungus Leveillula taurica and primarily affects leaves on pepper plants during warm wet conditions. Although the disease commonly occurs on older leaves just before or at fruit set, it can develop at any stage of crop development. Symptoms include patchy, white, powdery growth that can enlarge to cover the entire lower leaf surface Diseased leaves eventually drop off, leaving pods susceptable to sunscald.
Powdery mildew is managed primarily with fungicides. However sprays of sulphur and potassium bicarbonate have been known to have some success.
Verticillium Wilt is caused by soil borne fungus Verticillium dahliae is a soil borne fungi which can infect pepper plants at any growth stage. Cool air and soil temperatures favour it. This problem is particularly hard to pin down, as the symptoms are highly variable. Plants may show a yellowing of leaves and stunted growth. As the disease progresses, the plants can shed leaves and may finally die. If the stem is cut, a brown discoloration may be visible.
Crop rotation is the best control. Neither resistant cultivars nor chemical controls are known.
White Mold is caused by the fungus Sclerotinia sclerotiorum. It causes blighting or rotting of any above or below ground plant parts. At first, the affected area of the plant has a dark green, greasy, or water-soaked appearance. On stems, the lesion may be brown to grey in colour. If the humidity is high, a white, fluffy mold growth may appear.
Controls includes well-drained soil, proper plant spacing, crop rotation, and careful removal of all infected plants as soon as possible. Do not compost or use diseased plants for mulch.
Pepper Mosaic & Pepper Mottle Virus (PeMV) is caused when infected aphids and other insects come into direct contact with the plant. Stunted plants, distorted fruit, and yield reduction are all symptoms.
Aphids control and good sanitation practises. Planting resistant varieties is the best way to avoid this problem. Early detection and removal of infected plants helps, but complete control is often difficult.
Tobacco Etch Virus (TEV) is caused when infected aphids and other insects come into direct contact with the plant. Dark green vein bands, leaf distortion and stunted growth are all symptoms. Tabasco Chile plants are particularly susceptible to this disease and often wilt and die.
Aphids control and good sanitation practises. Planting resistant varieties is the best way to avoid this problem. Early detection and removal of infected plants helps, but complete control is often difficult.
Tobacco Mosaic Virus (TMV) is a highly infectious and persistent disease is carried by tobacco in cigarettes and is spread mechanically, by infected hands touching tools or plants. Symptoms can include curling leaves, spotted or mottled fruit, stunted plants and excessive leaf drop.
Smokers should disinfect hands (milk kills TMV) thoroughly before gardening. Growing resistant varieties is the best prevention. Early detection and removal of infected plants helps, but complete control is often difficult. Further Information Sources: The University of Maryland Cooperative extension www.hgic.umd.edu
What’s Bugging My Peppers?
As a northern gardener, you won’t have too many problems with insects bothering okra, peppers, and eggplant. Southern gardeners will have more problems. Here’s a rundown of the most common pests and what can be done for them.
Small and of various colors, these sucking insects can drain the sap from peppers, eggplant and okra all season long. If you notice ants near your plants, look for aphids. The aphids give off a sweet substance called “honeydew” that attracts the ants. Aphids also spread plant diseases, so be sure to control them if they’re a problem. To get rid of aphids, try spraying with a mild solution of soapy water or put out yellow pans of soapy water (aphids are attracted to yellow). If the infestation is severe, spray with pyrethrum.
Colorado Potato Beetles
These pests will feed on the foliage of eggplant and peppers. The adults are yellow with black stripes down their backs; larvae are reddish with a black head. Hand pick adult beetles and larvae every time you see them. Crush egg masses under leaves. They can be controlled by spraying with Sevin, pyrethrum, or a biological control called Bt San Diego.
The gray, brown or black worms chew tender transplants off at ground level. Cutworms are 1- to 1 1/2- inches long and curl up tightly when disturbed. They hide in the soil and attack at night. You don’t have to use anything to control them except newspaper cutworm collars at transplanting time.
These tiny black or brown bugs attack young peppers, eggplant and okra. They eat small holes in the leaves, usually early in the season, and if not controlled, can wipe out the foliage entirely, seriously injuring the plants. You can dust with wood ashes or spray with a garlic or hot pepper solution. Spraying with pyrethrum will also control flea beetles.
The adults are yellow flies with brown bands on each wing. They lay their eggs within the peppers, and the maggots feed from the inside out, causing considerable damage. If you see any maggot flies, spray with rotenone to control before they begin egg-laying. Once the maggots are inside the fruit, there’s little you can do but pick and destroy infested peppers.
Common in the South, these tiny black-snouted beetles are only 1/8 of an inch long. Don’t let their size fool you; they can cause a great deal of damage. Adult weevils feed on the foliage and lay eggs in the buds of immature pepper pods. When the eggs hatch, the larvae eat through the buds or fruit, causing them to drop or to be misshapen. There may be several generations a year. Dusting or spraying with pyrethrum helps to control them.
Tomato Fruitworm/Corn Earworm
Nearly 2-inches long, this pest is yellowish, green or brown with lengthwise light and dark stripes. It affects all three of these vegetables, boring into the pods or fruit. To control, cover the plants with a floating row cover to prevent adults from laying eggs, hand pick worms or spray with Sevin as soon as you notice them or the small holes they’ve bored into the fruit or pods.
Aphid control in peppers
Aphids are serious pests of peppers. Colonies are capable of phenomenal growth, and a single pepper plant or whole crop can be devestated seemingly overnight. As soon as an infection is noticed it should be dealt with – never delay and hope the aphids will go away, they won’t.
Aphids are small, oval-shaped sap-sucking insects. They normally have a green body, but they can be black – hence the common names “greenfly” and “blackfly” – and some species also occur in a red form. A large number of species are found in British gardens, and 14 of these have been identified on chilli and sweet pepper plants. However, three species are particularly common on pepper plants. The most widespread of these is the peach potato aphid (Myzus persicae). This species has a plump oval shape, and the adults are up to 2 mm long. They are normally green, but red versions do occur. Becoming increasingly common is the potato aphid (Macrosiphum euphorbiae). This species has a large (1.7–3.6 mm) and slender body, most are green and some may have a darker green strip running down the centre of their back. And finally, there is the glasshouse potato aphid (Aulacorthum solani), another large aphid measuring 1.8 – 3.0 mm.
Peach potato aphids (Myzus persicae) on the underside of a chilli pepper leaf.
The life cycle of an aphid
Aphids have a complicated life cycle, which includes both sexual and asexual reproduction, viviparous (giving birth to live young) and egg laying adults, and winged and unwinged forms. For the pepper grower it is important to understand how the pests overwinter, but a detailed understanding of their life cycle is only essential over the growing season.
In Britain the three main aphid species that attack peppers are polyphagous (feed on many different plant species). As long as temperatures are suitable, they may remain within the polytunnel or greenhouse residing on whatever plants are available – which often means using overlooked weeds. They also overwinter outdoors on whatever alternative host suits that particular species. For example adult peach potato aphids lay eggs on twigs of peach, plum and other related species.
During the growing season most greenhouse aphids are female and do not need a sexual encounter to reproduce. They do not lay eggs, but rather give birth to live young that are a perfect, though small, replicate of their mother. Not only are these newborns fully functional sap-sucking pests, but they are also pregnant – they actually have young developing inside them as they are being born themselves. In warm conditions the young aphids take about a week to grow and mature, before they too start giving birth to live, pregnant young.
Each aphid will give birth to about three to ten young every day for up to four weeks. Given these figures, in good conditions aphid populations can grow at alarming rates. When a grower notices signs of aphids on a pepper plant they should be dealt with immediately. If left alone it will not be long before there are thousands of aphids, and then hundreds of thousands.
The majority of aphids in a population are wingless, and they spread simply by walking from leaf to leaf and plant to plant. However, under certain conditions, particularly overcrowding, some aphids are born with wings. These can then fly away and infect a new plant elsewhere.
Damage caused by aphids
Aphids cause damage to the plants in several ways:
First and foremost, they weaken the plants by sucking the plant’s sap. Sap, a sugary solution that is passed around the plant, is the plant’s food, and any loss will reduce growth.
Secondly, as the aphids suck up large quantities of sap, they have to excrete the excess, which is a sticky solution called “honeydew”. The falling honeydew lands on the leaves and fruit below, which causes problems for the plants in two ways:
- The honeydew is sticky, and when it covers the leaves they collect dust.
- The honeydew is very sweet which attracts sooty mould growth, making the leaves turn black.
Black sooty mould growing on pepper leaf growing on honeydew dropped by aphids.
The effect of the dust and black covering of sooty mould on the leaves is to reduce the amount of light reaching the leaves. Without light photosynthesis cannot occur. Photosynthesis is the process within the leaves that makes the plants’ sugars, and is essential to the health and growth of the plants. In serious infestations little light reaches the leaves and photosynthesis will virtually be stopped.
The falling honeydew also makes the pepper fruit sticky and turn black, making them unappetising to the home grower and worthless for selling.
However, this is not the whole story; aphid saliva is also bad news for the plants:
- It contains toxins that cause the emerging leaves to be deformed. This happens more with the glasshouse potato aphid than with the other species.
- It carries viruses, and an aphid feeding on an infected plant will transfer the virus to all other plants it feeds on.
Aphids congregate within the young leaves in the growing tips of peppers and on the underside of the mature leaves. This means they are well hidden, and go unnoticed when infestations are at an early stage. However, there are certain tell-tale signs that indicate their presence:
- Distorted leaves emerging from the growing point.
- Scattering of white skin casings under the plant.
- Ants actively running over the plant.
- Sticky leaves. In addition, the area around the plant can get sticky.
- Leaves turn black from sooty mould.
The fallen white skin casings are a very clear sign of aphids; they are also the cause of a very common misdiagnosis. Young aphids shed their skins as they grow. Generally each juvenile will shed its skin four times before it reaches maturity. These skin casings fall to the leaves below, and as they dry they turn white. Many growers see these white forms on the plant and assume they have a whitefly problem. Though whitefly can attack peppers a serious infestation is rare – after growing chillies commercially for 22 years we have never had a whitefly problem on our peppers – even though we do regularly get whitefly on our tomatoes in neighbouring polytunnels.
A simple test is to shake the plant. Whitefly are literally white flies, and if the problem is whitefly the adults will fly up when the plant is shaken. Most aphids are wingless, and a hard shake may make them fall off, but they certainly will not fly.
Ants are often found near aphid colonies as they feed on the sweet honeydew. To protect their food source ants actively look after, or “farm”, the aphids, protecting them from insect predators.
Sticky leaves and sooty mould on the leaves are symptoms that occur when an infestion has become well established. For many growers the early tell-tale signs are harder to notice so these are often the first symptoms noticed. However, these symptoms will affect the plants’ ability to grow and immediate action to control the aphids is essential.
An aphid infestation must never be ignored. Aphids can be controlled quite easily, but it is an active process, they will not go away by “forgetting” they are there.
There are three approaches to control for a home chilli grower:
- Biological control
There are several insects that prey on aphids. The species that most gardeners are familiar with include:
- Parasitic wasps
Ladybird larvae enjoying an aphid meal.
Many of these “good guys” occur naturally in the garden, and a gardener should do their best to encourage them. It is well worth a gardener learning the life cycle of these insects, but most importantly, becoming familiar with what they look like. Of course, most people, easily recognise the adult stages of ladybirds, lacewings and hoverflies, but very few gardeners know what the eggs, pupa and juvenile stages of these species look like. An hour on the internet can easily remedy the situation, and would probably be one of the most valuable hours spent on the garden!
Ladybird larvae (left) and pupae (right) on a chilli pepper leaf.
Most outdoor areas will have some beneficial insects in residence that will maintain some level of aphid control without the gardener ever knowing. However, the indoor environment of a windowsill is unlikely to have any insect predators occurring naturally, and chilli plants kept indoors as a house plant will have no defence against an aphid infestation. Still it never hurts to bring in any ladybird found outdoors to reside on a favourite plant!
Adult and juvenile ladybirds eating aphids on fathen, an outdoor weed.
As well as maintaining an envirionment that encourages the presence of naturally occuring insect predators, it is possible to buy-in predators and parasites. These are sent out through the post, and once released into the polytunnel or greenhouse, will provide aphid control and bred themselves thus increasing their populations. Though not cheap this is the method recommended for all gardeners with plants in a polytunnel or greenhouse.
For the home gardener and small commercial operations we recommend Agralan (www.agralan.co.uk), a company that is dedicated to protecting crops through biological control. For large commercial growers whose orders will satisfy the minimum order restrictions, there are a number of companies that provide a complete control programme through biological control.
Releasing parasitic wasps into a polytunnel with a chilli pepper crop.
Left: aphid mummies formed by the parasitic wasps laying an egg in the aphid.
Right: a single aphid mummy with with a round hole where the parasitic wasps escaped.
Releasing commercially bought ladybird larvae into a crop of Hungarian Hot Wax chillies.
Growers who take their chilli growing very seriously are recommended to start buying in predators before they see any signs of aphids. This army of “good guys” will seek out the aphids and deal with them long before even an alert grower is likely to find them.
The mantra to follow for biological control is that it is a “numbers game”. If there are enough beneficial insects, aphids will be controlled. If predator numbers are too low, the aphid colonies will grow. The later you start using biological control the more predators or parasitoids will be needed.
Unfortunately, insect predators are not a realistic option if you keep just one or two chilli plants on a windowsill in the house or conservatory. See below for more information on controlling aphids on house plants.
Prevention is always better than cure, and the predator option is undoubtedly the best method of aphid control. However, if an infestation does occur it means there has been an imbalance between predator and aphid populations, and a more proactive control method is necessary. In other words, once an infestation has become established, whether it is on a single plant in the house or in a large commercial greenhouse, will not clear up on its own, the plants will not recover without an intervention.
Before resorting to pesticides we recommend trying water as a control method. Water is safe, effective and because of the sticky honeydew, aphid-infected plants will always need to be washed down anyway. Aphids do not hold on tight and a blast of high pressure water – a finger on the end of a hosepipe or the cold water tap on full – will knock them off the plant. Most effort should be applied to the growing points and the underside of the leaves as this is where the aphids congregate. If the plant is in a pot lying it on the ground or turning it upside down will give full access to under the leaves. Water does not kill aphids and they will readily walk back onto the plant. So if the plant is in a pot do not wash it near where it is normally kept and wash down the area before returning it to its place. If the plants are in the ground this is not so easy, but if it is possible wash/brush down the area as well as the plant.
It is unlikely that one wash, no matter how thorough, will remove all the aphids. So to get a complete control repeat the operation the next day…. and the next if necessary. Some customers say washing doesn’t work; most likely the failure was due to a half-hearted wash; a thorough wash means THOROUGH.
Pesticides are substances or a concoction of substances that kill pests. They can be either natural or synthetic and they work in different ways; some are potent poisons, others cause death through a physical process. Some have very specific target pests, others are generalists and an application will have a universal kill. All should be used carefully and with a full understanding of how to use the pesticide and the objective of the application.
When buying a pesticide always read the label. Be sure it is recommended for use on peppers, and if you keep the plant in the house, it must state that it is suitable for “houseplants”. In addition, the pesticide must state it is to be used to kill aphids (the packaging may say “greenfly” or “blackfly”); remember whitefly is not another name for aphids. All retail stores selling garden pesticides to the home gardener must have someone at the available who can advice you on the use of pesticides. Commercial growers are governed by different laws, they can buy stronger pesticides from suppliers that are unavailable to home gardeners, but now must take specific pesticide application courses and then be registered.
Chemical pesticides: These are powerful, toxic chemical pesticides can be bought to kill aphids. A perusal in any garden centre will reveal a whole host of brands available to the home gardener. Many are systemic, which means they work by being absorbed into the plant so the aphids are killed when they digest the poisoned sap. Unfortunately, these pesticides (poisons) will be transported throughout the plant, including the parts of the plant we eat. It is essential the instructions are followed carefully, including the withdrawal period, i.e. the time that must elapse between applying the pesticide and consuming the peppers picked off the plant. The plus side of systemic pesticides is that they specifically target the sap-sucking pests. However, you should check the compatibility of individual pesticides with natural predators as some chemicals can kill natural enemies for up to 8 weeks (check the biopest side effects list).
Physically acting pesticides: There are several compounds that are relatively benign to the environment and humans. They work through a physical action taking advantage of the insects’ small size or physical shape. Many are so safe they are considered acceptable for organic growers. A common active ingredient is a fatty acid, but there are others, e.g. SB Plant Invitorator, which kills simply through a physical action – the packaging states: “aphids, juvenile whitefly and spide mite if directly hit are trapped by its wetness”.
A search on the internet will reveal several companies that sell these pesticides, but the one we recommend is: www.harrodhorticultural.com
As these pesticides work through a physical action they can only be effective when a 100% coverage is achieved – this is so important the instructions on some state the liquid should be applied until it drips off the plant.
Applying Eradicoat, a sticky solution made from cornflour, to kill a bad infestation of aphids on a poblano chilli crop.
Unfortunately the physically acting pesticides kill all species of small insects and mites, including the beneficial species. Consequently, where beneficial insects are present in a crop it is often recommended to only apply the pesticide where the aphid colonies are worst. More beneficials can then be released as soon as the crop has dried after spraying physical products as there are no residual effects.
Dead aphids after an application of Eradicoat; the “aphid mummies” are not hurt by the Eradicoat.
Some people make up their own home-made concoction to kill aphids. A common one is diluted washing up soap. Washing up liquid contains many more chemicals than just soap, some of which are bad news to a growing plant. So while such a solution may kill the aphids it may also kill the plant. In addition, under UK and EC law it is illegal to use any home-made mixture as a pesticide – the law states only preparations approved as a pesticide can be used specifically to kill pests.
The chilli plant as a house plant
Certain chilli species are very attractive when grown in pots, and as they like the warm, sunny conditions typical of a sunny windowsill or conservatory they do make excellent houseplants. Unfortunately, chilli house plants are not spared the risk of an aphid infection. As aphids reproduce asexually it only takes a single aphid to get into the house – maybe a winged one through an open window or possibly hitching a lift on a human or pet – to start an infestation. The home environment does not encourage the presence of natural preditors, so once an aphid colony has become established it is likely to grow at a frightening speed and quickly destroy a plant.
Chillies make very attractive houseplants.
As a precaution it does not hurt putting ladybirds on a chilli house plant as they will seek out and eat any aphids that arrive. However, once an indoor plant is infected the best thing is to give the plant a thorough wash. It is unlikely all the aphids will be removed by a single wash, so repeat the wash every day for the next three or four days.
All pepper growers will experience an infestation of aphids on their plants at some time in their growing career. There is simply no way of avoiding the pest, and anyone who has not had a problem with aphids just haven’t YET had a problem.
But an aphid invasion is not the end of the world. Do not throw away your precious house plant – as some people do. Nor should you allow the aphid population to continue to grow. Deal with the aphids and reclaim the health of your plant.
- Knowing and recognizing: The biology of glasshouse pests and their natural enemies. M.H. Malais and W.J. Ravensberg. Published by Koppert B.V. ISBN: 90 5439 126
Thanks to Clare Sampson, consultant entomologist for BCP Certis., for reading this article and checking for accuracy.
© Joy Michaud
Aphids On Pepper Plants
Reducing Aphid Damage
Aphids are a natural part of the ecosystem and eradication isn’t necessary. For the most part, the damage they do will not kill your plant, and they tend to attack already weakened plants. Instead, focus on the realistic goal of reducing the damage they cause on plants. There are several ways:
- Homemade Insecticide
Use water to blast the insects off of the underside of the leaves. A spray nozzle on a garden hose works best. Use this technique in severe cases. The aphids will not come back to the leaves, but it is not a long-term solution. It will give you enough time to implement some other strategies.
Aphids have many predatory insects, and encouraging them to come into the garden is the best way to control aphids on a long-term basis. When in a pinch, you can order some of these insects through the mail and have them ready to work in a couple of days. Here are some aphid predators that are commercially available:
- Ladybugs: Spotted beetle that eats aphids, mealy bugs, mites and scale insects.
- Lacewings: Flying insect that eats aphids, mealybugs, mites, caterpillars, thrips and whiteflies.
- Pirate Bugs: Beetle that eats aphids, mealybugs, mites, scale insects and thrips.
- Parasitic Wasps: Specifically seek aphids for egg laying.
Some gardeners will make a mixture of unpleasant ingredients that is meant to both kill and deter aphids from feeding on your plants. Many of these mixtures contain cayenne pepper. Keep in mind the capsicum that makes a pepper spicy isn’t in the leaves of the plant, only the fruit.
Homemade insecticide includes one garlic bulb, one small onion, and a few teaspoons of dried cayenne pepper powder. Mince the garlic and onion and mix them with the cayenne in a spray bottle full of water. You can strain the mixture through a cheesecloth after soaking overnight if you prefer.
Spray this mixture on the undersides of all your pepper plants leaves. Not only to aphids hate onion and garlic, but the cayenne may help to also deter them from ever returning.
Ideally, aphid populations will swell and decline throughout the year without doing much damage to your plants. Maintain habitat for your predatory insects and plant aromatic herbs which repel pests. The healthier the plants are the less vulnerable they are to damage.