Papaya or papaw is a popular tropical fruit. Even though papaya grows in the tropical region, papaya fans live worldwide. Consequently, many people tend to grow papaya trees in their home gardens or farms. So, this article is most valuable for people who grow papaya trees or wish to grow papaya near future.
Generally, many diseases of papaya trees arise due to various causes. However, first, you should treat your tree well. It will help to reduce the risk of infections.
Anyhow, here I mentioned the most common diseases related to papaya trees. But keep in mind preventing is better than controlling.
Foot or stem rot papaya, Anthracnose, Powdery mildews, papaya leaf curl disease, papaya ringspot disease, and papaya mosaic disease is the most common diseases of papaya trees.
However, it is vital to know the symptoms and treatments to manage the disease properly. That’s why you should know the below facts.
Foot or stem rot papaya
Many people recognize this disease with various names. It can be foot rot, stem rot, root rot, or collar rot. Whatever the name you have known this disease, this can be serious if you do not recognize it early.
You can notice the water-soaked patches near the ground level on the papaya stem. These patches enlarge and spread rapidly and then girdle the stem of the papaya tree. However, this happens due to rotting tissues. Over time these patches turn black or dark brown.
But in some cases, you can identify white, fluffy growth of fungus. Also, it causes yellowing of the leaves. Then eventually papaya tree dies.
However, if a disease attack is mild, it causes rot the one side of the stem. Consequently, the papaya plant remains stunted. But at last, the plant will die.
unfortunately, if your papaya tree shows the symptoms of stem or foot rot. It isn’t easy to save. The only thing you have to do is dig up the infected papaya tree and destroy it.
Also, do not try to plant more papaya trees in the same spot. Because fungi live in the soil to seek another host.
In addition to that, you can prevent foot rot disease by following the below activity.
Generally, these fungi develop in damp conditions. So, waterlogging of papaya tree’s roots causes to rot the stem. Therefore, plant your papaya tree in well-draining soil.
Anthracnose can be categorized as a serious fungal disease. The cause is pathogen Colletotrichum glowosporioides.
You can identify the symptoms in the field and at the storage of papaya fruits. Firstly, you can find out the spots on fruits that are brownish superficial skin discoloration. These spots develop into circular, slightly sunken areas, which can be around 1 to 3 cm in diameter.
Over time, the lesions coalesce, and sparse mycelia grow on the margins of the spots. When fungus produces spores, these spots gradually turn pink. Also, the papaya fruit beneath gets extremely soft.
If you identify the spots on the papaya fruits, it will help you to recognize the anthracnose early. So, you can start treatments to your papaya tree early too. Basically, if you identified that the disease is present, use the proper sanitation method.
Identifying the disease early means that you can avoid using chemicals when treating anthracnose. Instead of leaving it on the tree, you can follow cultural control measures, for instance, harvesting matured papaya fruits promptly.
Also, you should remove all dead fruits and leaves. Similarly, you have to pay more attention to get all those falls under the papaya trees. In addition, you can prevent the spread of this disease from rain splashback and plant to plant attack by cleaning weeds or debris properly in your garden. Further, do not forget to sanitize the tools that you used.
Also, you can use preventive fungicides to control papaya anthracnose. Here it is better to use a fungicide containing Mancozeb, Copper hydroxide, Bacillus, or Azoxystrobin. However, you spray the orchard with the fungicide every 2 to 4 weeks.
This disease can occur in papaya trees at any stage of age. The cause of this disease is the fungus Oidium caricae-papayae.
you can notice the patches of whitish powder growth on the undersurface of diseased leaves. Also, the upper surface of the leaves at the infection site appears blotches of pale green or yellow. These blotches are usually near veins and surrounded by colored tissues.
In some cases, if fungus develops under reduced light conditions, you can discover that the fungus attacks the stem of the young seedling. Gradually, these spots will enlarge and cover the whole papaya leaves. If leaves are infected severely, they can become chlorotic and distorted before falling.
However, this fungus develops under the surface of the papaya leaves by absorbing nutrients from the leaf surface cells through a specialized absorbing structure, namely, haustoria.
We can follow organic or chemical treatments to control powdery mildew here.
If you prefer to go with organic control, you can use Wettable sulfur, sulfur dust, potassium bicarbonate, or lime sulfur to control this disease. But do not apply these in hot weather because they can be toxic.
Sometimes neem oil extracts, baking powder, soap solution may work. But if the disease is severe, these treatments may not be effective.
When it turns to chemical treatments, you can use fungicides such as mancozeb and azoxystrobin to control powdery mildew on papaya.
Papaya leaf curl virus
The most common appurtenance of this disease is curling, crinkling, and distortion leaves. Also, we can see the reduction of leaf lamina, thickening of papaya leaves veins, and rolling of leaf margins inward and downward.
Further, affected leaves become leathery, distorted, and brittle while stunting the papaya plants. Not only that, diseased plants do not produce flowers and fruits.
In some cases, you can notice that all the leaves at the top of the plant appear these symptoms. When the disease is severe, the growth of the papaya plant is arrested.
Under organic treatments, you can spray white oil emulsions (1%). It helps to hinder the uptake and transmission of the virus through aphids.
However, there is no chemical treatment to control this viral infection. But you can reduce the whitefly population by spraying 4 to 5 foliar sprays of dimethoate or metasystox at an interval of 10 days. Hence it can reduce the severity of the infection.
Papaya ringspot disease
The initial symptom is chlorosis on the youngest leaves. Then gradually diseased papaya plant shows vein clearing, rugosity, and prominent mottling of laminae. Also, you can notice malformation and reduction of the lamina.
Further, elongated dark green streaks develop on the upper half of the stem, petiole. Also, there are circular concentric rings on infected papaya fruits.
Not only that, this disease can reduce 56 to 60% yield.
Unfortunately, it will be more challenging to control when the disease is established. So, it is better to destroy the affected papaya plant to protect other plants.
However, you can try out insecticides containing flonicamid, pymetrozine, imidacloprid, and acetamiprid. The thiamethoxam, sulfoxaflor, chorpyrifos, cypermethrin, and bifenthrin are also good for this disease.
Further, you can use spray bale products containing one or more of the following molecules as organic treatment.
- Neem oil
- The potassium salt of fatty acids
Papaya mosaic disease
diseased plants show leaf mosaic and stunting. Also, you can notice vein clearing and downward cupping of the leaves on young seedlings in the greenhouse about 5 days after inoculation.
Further, gradually after 15 to 20 days, mottle and mosaic develop. Most probably, you can see symptoms firstly in the young leaves of your papaya plants.
Commonly these diseased leaves are small in size, and there are dark green patches otherwise yellowish-green leaf blades.
To disinfect, you should heat the working tools in an oven at 150 degrees Celsius for about 1 hour. Because it will help kill the virus and reduce its spread.
Alternatively, it is better to dip working tools or gloves in 0.525% sodium hypochlorite to kill the virus. Then rinse them in water properly.
However, there is no chemical treatment to treat this viral infection. Here only you have to do is destroy the infected plants as soon as they show the symptoms. Because it will cause to save other papaya plants from this disease!