The fruit that has revolutionised diets and become a mainstay fruit in cafes and restaurants across the world has absolutely no intention of disappearing from the limelight anytime soon.
However, every hero needs a villain, even if that hero is a fruit.
Avocados Encounter Pest Problem
Avocados ran into a bit of trouble with pests last year when the Colombian Agricultural Institute (ICA) announced that unforeseen pest problems would lead to import suspensions. A statement from the ICA read:
“The ICA (Colombian Agricultural and Livestock Institute) continues the surveillance and eradication program for Hass avocado quarantine pest in 21 municipalities located in 7 departments of the country.”
They went onto claim that 2018 will see a potential ‘20% increase in the total exports of Hass avocados from Columbia to Europe and North America.’ Last years estimate for exports equated to roughly 26,000 – 27,000 metric tons with a value of £37 million pounds.
Despite this, there are growing concerns that the obsession (and therefore supply and demand) of avocados will lead to increased chances of pest encounters. Below are some of the main pests that pose a threat to avocados.
High priority exotic pests
There are only a few main pests that cause a threat to avocado trees. However, it is important to understand why avocado trees are under threat from such pests in the hope that farmers can take the necessary precautions to ensure that their crops and our food is no affected.
Different pests occupy different areas:
This is arguably the most common disease for avocados. While scabs on avocados are very common and usually harmless, they can become an entry for fruit rotting organisms such as anthracnose. This is why treating avocado scabs is a very important step to ensuring the rest of the crop will not be affected. Additionally, it will better enable the farmer or grower to apply avocado scab control.
Signs of avocado scab:
- A fungal disease that causes markings on mature fruit, brown in colour.
- Discrete spots and marks appear on the leaves as well as the midrib. These may merge into star-like patterns.
- If the disease progresses, leaves will become distorted and stunted.
- Purple/brown spots and marks will become bigger and cover larger areas.
- Dispersal inevitable – especially if markings are left untreated.
Avocado Seed Moth
Quite unknown to the daily avocado consumer and it’s no wonder why. Seed moths are usually found in Peru and Brazil and are notorious for infesting avocado crops. Larvae have been found feeding and festering inside avocados. If two are present within the avocado, they have the ability to complete destroy the fruit from the inside out.
Symptoms of the seed moth:
- Common pest in Latin America causing huge crop losses.
- Larvae are initially white but become violet during later development stages.
- The larvae penetrate fruit and destroy seed and pulp.
- Frass can be seen in fruit when opened and white exudate may occur externally.
In the 1920s, the disease was originally thought to be a genetic disorder. However, several decades later, biologists confirmed that the disease was actually caused by a viroid, an infectious entity smaller than a virus. The virus can be difficult to identify because it has such a variation of symptoms. The most common are:
- Student growth
- Red, white or yellow discolorations on the fruit (including sunken areas)
- Fruit becomes misshapen
- Red, white or yellow streaks on bark or twigs
There are over 6,00 Thrips species feeding off plants across the globe. They damage plantation by sucking the nutrients out of them, turning them pale, withered and eventually die. Thrips are also responsible for spreading tomato spotted wilt virus. They have become a particular nuisance to avocados, so much so they caused large economic losses in California last year.
The symptoms of avocado Thrips are:
- Bronzing along leaf veins (a sign of severe infestation)
- Alligator-like skin appearance
- Scars elongate as fruit grows and develops, causing poor quality fruit
Laurel wilt is a vascular disease which is transmitted by the Ambrosia Beetle. The disease affects and kills members of the laurel family – the avocado being the most valuable plant affected. Laurel wilt can spread in a matter of days: one way is via the beetle’s reproduction and migration and the other way is through the transportation of beetle-infested wood.
The symptoms of laurel wilt are:
- Fungal disease emanating from avocado trees (Florida)
- Wilting leaves and foliage
- Beetles will swam dying trees – look out for them!
Persea mites damage avocado trees by removing chlorophyll from the leaves when feeding. Due to this, the leaves are far more likely to drop from the tree. Healthy leaves are obviously critical to the survival and growth of an avocado tree. If the avocado tree is damaged by persea mites, it can negatively impact the farmer or grower’s profitability.
The symptoms of persea mites are as follows:
- Nests forming along midribs and veins of avocado tree leaves
- Leaves are covered in necrotic spots covered in dense webbing
- Defoliation and yellow-spotted green leaves spotted under trees.
Don’t worry, it’s not the end of the world!
It’s always important to stay observant of pests in food. While these avocado pests are not inherently native to Europe, you’d be wise to keep a look-out, just in case. Pests like Thrips are native to the UK and Europe and if you do own your own avocado plantation, or even tree, you do not want to experience a pest infestation.