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Growing Tips for Beginners

Following on from Part 3, where we covered removing pups, watering and fertilizing, we now finish by looking at the basics of controlling common diseases and pests – and also protecting your broms from the elements.

Disease Control

Thankfully, bromeliads are relatively hardy and generally not susceptible to a wide range of problems, though there are a few common ones you are certainly likely to strike. The “disease” or “rot” we normally see, is actually fungal growth that thrives on high humidity and poor air circulation around the plant. Therefore as a general rule, firstly ensure plants are not planted or kept jammed too close together -and they always have a good air flow around them. Broms in the garden normally do not suffer from this problem as much as those indoors or in greenhouses, where the air circulation can be vastly reduced.
The most common fungal disease (normally phytopthora) will often attack a weak spot in the plant where damage to the leaf has occurred from such things as sun scorch, cold spotting or heavy metal poisoning.
As mentioned in part two, bromeliads do not like ANY contact with treated timber and also exposure to copper and zinc, where the smallest doses can cause severe burning to leaves.
Secondly, always ensure any water run-off from treated timber, galvanized shelving and nails etc, does not land on plants below. After damage occurs, that part of the leaf will die and quickly start to rot, which is where the fungus can attack, enter the leaf and quickly spread. This is very common in the vase (cup) of the tank forming broms, near the base of the outer leaves and sometimes in the very base of the plant at or below the soil surface (known as “Footrot”). The diseased tissue looks brown, grey-bluish, black or transparent in colour and often has a bad smell (see photo).
For treatment, tip all the water from the plant, cut out any rot and completely remove all loose and rotted leaves. Thoroughly clean and rinse the plant with clean water a few times so no rotted tissue is left behind, then generously spray with a fungicide such as Yates Bravo or Fongarid 25WP at the recommended mix rate for ornamental plants. Allow it to dry out for a few days before watering, then monitor for further attacks and to ensure new undamaged growth is occurring. 

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Typical “cold spotting”, not a disease – very common on foliage Vriesea.

 

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Here fungal disease has attacked leaf damage, likely caused by treated timber poisoning or hot water from the hose in summer.

 

Pest Control

Scale sucking insects will attach themselves to any part of a leaf, often on the sheltered underside. They can be fluffy white, grey or small and black and cause yellow/brown spots, which permanently damages the leaf and can look very unsightly. Scale can be physically scraped and wiped off with a cotton ball soaked in methylated spirits, which will kill the eggs and microscopic “crawler babies” that are hard to see.

Mealy bug can also attack the leaves and is sometimes also seen around the roots if a brom is removed from a pot or the garden. This is also fluffy white in appearance and can be treated as for scale above if on a leaf. For root attacks, it can only be treated by spraying with a suitable insecticide, or alternatively cutting the roots almost completely off and starting the plant again as if it were a pup. Ensure the any infested potting mix and root material is carefully discarded, so it is not spread to other plants.
For more widespread infestations of scale and mealy bug on leaves, mix a little Sunlight dishwashing detergent or baby shampoo with water and thoroughly spray the infected areas. The soap coats and suffocates the insects. After a while, rinse the plants off with clean water so pores on the leaves open, allowing the plant to breathe. DO NOT use heavy oil based insecticides, as these can often clog and choke the plant.

Slugs, snails, earwigs and weta do not normally cause major damage but will often use the leaves for a place to hide and breed. However, they have been known to gain “appetites for destruction” all of a sudden, especially on new leaf growth, flower spikes and pups that are forming. So, the best precaution is to simply get rid of them when they are seen. Slug bait does the trick and being brave to find a new home for your weta is the best idea.
If you have bad earwig infestation, insecticide spray again is probably the only cure.

Mosquitoes are the other major pest associated with broms, and are common in the large open tank forming genera, where they have plenty of warmth and stagnant water for the larvae to develop. In summer, check for dark wriggling larvae and flush out the cups regularly with a hose if they are present. You can also make up a spray using 500ml Sunlight dishwashing liquid; 200ml household cloudy ammonia; 100ml Citronella or Pine-o-Clean disinfectant. Mix and pour the contents into 5 litres of cold water and keep it in sealed bottles. Then use 3 tablespoons per litre of water for spraying the plants every week until no larvae are seen. The mixture kills all wrigglies and will not harm the broms. Alternatively you can liberally sprinkle spent coffee grounds over the affected plants, the caffeine soaking into the water will eventually kill the larvae too.

 

Sun and Frost Protection

Overhanging trees and shade cloth and are your best protections for summer sun, where some broms can be badly scorched if there is not adequate cover. Using 50% to 70% beige, white or black coloured shade cloth appears to give the best results for most broms to gain and retain their best colour in our climate. In winter, exposed areas of the garden may be susceptible to frost – most bromeliads DO NOT handle frost and extreme cold that well. If the broms cannot be relocated to a more protected overhead area, pegging up 2 metres x 5 metres lengths of frost cloth on string or wire over the plants is a good idea the night before a frost is forecast. Also spraying the plants with Vaporguard (available from Kings Plant Barn etc) helps the plant reduce transpiration and heat loss, so it can handle temperatures below zero degrees without causing leaf burn.
All the preventative effort is worth it, as frost damage on prize broms is a sickening thing to see (see photo).
However, DO NOT throw heavily frost-burnt plants away if you are unfortunate enough to become a victim. Fertilize them well in spring, use Seasol Conditioner in the soil and cut off all the burnt leaves. The plants will look terrible after trimming them, but within a year the new growth from the centre cup should have emerged and you will have new broms to enjoy again!

 

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This plant actually has some unburnt green centre leaves down inside the cup.
Two years on it’s now perfectly healthy!

 

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Heavily frost damaged Alcantarea imperialis plants from minus 3 degree celsius frost in 2009.

 

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