Common problems when growing chilli plantsSusan Carter
Now that you have germinated your chilli seeds, or maybe you have just bought some seedlings, you are looking forward to a productive season of growing chillies. However, there is still a lot that can go wrong and prevent you reaping the harvest you desire. Here are few of the more common problems you may encounter when growing chilli plants.
Insects and other pests
Slaters love to chew the stems, so if you can’t surround your pot with something or keep it away from slaters you may need to put down a deterrent such as slater dust.
The same goes with slugs and snails especially at seedling stage. Try using a pot that has the bottom cut out to surround your seedling or a soft drink bottle with the bottom cut out and the lid off. You can also buy copper tape to put around your pots. This will stop snails and slugs from feeding on your plants as they can’t cross the tape because the copper gives them a shock and they back away.
Caterpillars, worms and larvae do major damage to pods. They get inside and lay their eggs, damaging the pod and making them useless. Some varieties can even overwinter in the plant and soil. You need to eradicate them as soon as possible and remove all affected pods. Dipel can be used as an insecticide or you can pick them off by hand.
You need to check the underside of chilli plant leaves for aphids. They love to hang around fresh new growth and flowers. If you find any, you can spray them with a natural pyrethrum, Confidor (highly recommended) or with a garlic and chilli spray. Check after a few days and if they are still there repeat the process.
Aphids suck the sap out of your leaves and can really make the plants suffer as well as dropping their leaves. They can be a clear to green colour and once they have been sprayed or killed will turn into brown mummies. When you have severe infestations you may also spot small, white, rectangular shapes. This is actually caused from the aphids shedding their skin. Lady bugs are also natural predators and ants are the culprits of giving these monsters a ride to your plants. The aphids actually hitch hike on the back of ants. So if you have an aphid problem and also spot an ant problem make sure to get rid of them too! Other biological and safer ways are available, check out http://www.biologicalservices.com.au/ for some natural predators to solve your unwanted pest problems.
Thrips are another damaging pest. You can find a variety of sprays in your local garden centre or Bunnings.
Recently the Tomato Potato Psyllid has been found in WA. This is a serious pest and can damage crops. There are more details here: https://www.agric.wa.gov.au/tomato-potato-psyllid-tpp
Viruses & Diseases
Fungal problems can occur from overwatering and humid conditions. It is best to water your plants in the morning to avoid your plants staying wet overnight. If they need an extra drink in the evening it is recommended to water them directly at the base of the plant rather than overhead watering and splashing on the leaves.
Fungal problems can also be air borne and can spread very easily. It is important that when you see an affected plant that you immediately quarantine it until you find out what is wrong and treat it or burn and destroy it before it spreads to your other plants.
When germinating seeds it is important to have sterile conditions and use fresh potting mix (not bags that have been left open for months or years). Also when you are potting your plants make sure you sterilise the pots if they have been used before as well as any tools. You can use household bleach or even pool chlorine. Make sure you soak for a minimum of 3 hours.
Damping Off can be a real problem with tiny seedlings. It is caused by one of several pathogens (Pythium species and Rhizoctonia solani for example) which thrive in damp, poorly ventilated conditions. The stem becomes thin and pinched, either above or below the soil level, and the seedling quickly withers – it can even be a cause of apparent non-germination. There is no cure, but remove and destroy affected seedlings. To help prevent this happening, make sure your seedling mix and pots are sterile, and increase ventilation.
Flowering and fruiting
We get a lot of questions about the superhots dropping their flowers or not producing fruit. The most common reason is that the plants are getting too much sun. Other reasons could be too much or not enough nutrients or the flowers not pollinating properly.
Here are some tips to prevent this:
Chillies are self pollinators so they do not need bees to pollinate their flowers. However sometimes they may need a hand. You can help by giving your plants a gentle shake in the afternoon (when pollen is at its most) or by using a cotton bud tip or your fingertip and rubbing it on the inside of each flower helping it to reach the stigma.
Excessive nutrients and nutrient deficiencies are the next most likely.
Potassium is the most helpful nutrient. If you do not have enough potassium then the flowers will not develop to full size. It is also a reason for small harvests. Phosphorus is also needed in higher doses during blooming.
A deficiency in calcium can also prevent uptake of other nutrients even if they are present. Calcium also affects flower setting and could be a reason for aborted flowers.
Excessive Boron can give similar symptoms to Calcium deficiencies. Also if you have too much potassium then it makes it hard for the plant to take up the boron. Boron is important in seed production as well as pollination.
Manganese is another nutrient that helps with pollen germination and can be immobile in high PH soils.
It is good to use a fertiliser which contains the macro and micro nutrients. You can try a slow release like NPK Blue.
Epsom Salts sprinkled on the soil add magnesium, and this can help ‘set’ the flowers. Lack of magnesium also causes yellowing of the leaves.
Brunnings brand Potash Power is an advanced sulphate of Potash formula that can be fed to your chilli plants either dry or in a soluble application. Not only will it help with flowering and fruit production but will also increase resisitance to stress and disease. Use this if your plants are showing scorching around the edges of the leaves, dull grey leaves and weak flower stalks or there is insufficient flowers.
Seasol is good to use once a fortnight to promote healthy roots and help in stressful conditions. If you spray it on the leaves of your chilli plants it also changes the PH of the leaf surface which helps prevent fungal problems. I also like to use Seasol when potting on as it reduces stress and makes the plant stronger.
Yates Uplift, Miracle Grow or Thrive can all give good results, and of course we use Chilli Focus on our plants, as this contains all the minerals and trace elements that chillies need to grow and thrive.
Never fertilise in the middle of the day or when you are expecting temperatures 35 degrees or more as this will burn your plants and do more harm than good. Best time is early morning or in the late afternoon/early evening. Applying nutrients to the leaves (foliar feeding) is more effective than feeding through the roots. Smaller droplets are also absorbed better than large droplets, so rather than drenching try using a spray bottle. Uptake is quicker and much more efficient.
If you think you have ever over fertilised your plants immediately flush your plants with PH adjusted water.
For advice on starting your chilli plants from seed, check out our blog here. Happy growing!