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Almost all garden plants, including lettuce, are susceptible to disease in some way.
Some are minor annoyances that are easy to avoid, but others can kill crops and infect soil, resulting in long-term crop loss if you don’t have enough area to rotate.
It’s a tremendous disappointment if you’re producing your salad greens for healthy, local salads and discover your plants have disease symptoms.
A lot of diseases affect lettuce but today we are going to discuss 5 main common causes of lettuce disease.
1. Downy Mildew
Lettuce that has been exposed to cool, wet weather for an extended period is extremely susceptible to this fungus-like infection.
Yellow or brown stains on leaves, wilting, and the formation of fluffy mould, usually on the underside of leaves, are all symptoms of this illness.
It’s crucial to remember that downy mildew might resemble powdery mildew in appearance.
Water moulds (oomycetes) from the Peronospora, Plasmopara, and Bremia genera cause powdery mildew, whereas water moulds (oomycetes) from the Peronospora, Plasmopara, and Bremia genera cause downy mildew.
A fungicide treatment will not solve a downy mildew problem.
How To prevent
- Once indications of this illness have been identified, it is preferable to remove and destroy any afflicted leaves. If a considerable area of the head is afflicted, it’s preferable to get rid of it as soon as possible to avoid the disease spreading from plant to plant or into the soil.
- The best cure is to avoid it in the first place. Allow enough spacing between plants when planning your garden space, since this can help to prevent more than one sort of illness.
- Plants with insufficient space can easily transfer disease and infestation.Check the seed packet for instructions on how to space your seeds.
- During periods of cool weather, avoid overwatering and don’t let water sit on leaf surfaces. Make sure loose, low-hanging leaves aren’t resting against the soil beneath them or squeezed against neighbouring plants.
- Use drip irrigation, which allows water to soak straight into the ground instead of drenching the foliage, or water at ground level if possible.If feasible, use a fan or blower to increase air circulation, which will keep plant surfaces drier and help them dry faster.
2. Bacterial Leaf Spot
Black lesions on the outer leaves, typically accompanied by yellow discolouration known as “halos,” are the most common symptom of bacterial leaf spot. These are more common on older heads than on younger plants.
Bacteria from the Xanthomonas and Pseudomonas genera are the principal culprits of this disease.
How To prevent
- If you notice symptoms of leaf spot, keep in mind that the illness is transmitted by splashback from watering, which can be mitigated in part by utilizing drip irrigation or ground-level watering rather than sprayers or sprinklers.
- You should also avoid overwatering, although be aware that rain might still spread bacteria.Planting infected seeds is another technique to transfer the bacteria into the garden.
- Because these bacteria have a ten-year shelf life, you should avoid preserving seeds from sick plants or those grown nearby if you’ve had an epidemic.
- By soaking seeds in a bleach solution to sterilize them, you may be able to destroy germs that are present on the seed surfaces, even on seeds that you’ve purchased.
- Spray a commercial copper fungicide on young plants before the beginning of disease symptoms.If you’ve planted from seedlings or store-bought stars that were sick at the time of purchase, this can assist in eliminating germs that have survived seed sterilizing.
3. Mosaic Virus
Unfortunately, the mosaic virus is fairly widespread in home gardens. It can spread from plant to plant through contaminated seed or by hungry aphids puncturing plant leaves to collect fluids.
Stunting, chlorosis, or bleach-like spots, dull, malformed leaves, blistering, and ragged leaf edges are all indications of infection in lettuce.
In short, once you know what to look for, the lettuce mosaic virus is rather evident and easy to spot.
The yellow-green mottled hue of diseased leaves gave rise to the term “mosaic.” Please keep in mind that symptoms can vary according to your seasonal climate, so you may not see all of the symptoms listed below.
The discolouration is more prevalent in humid regions, although you may have less of an issue with the virus in cooler, drier settings.
How To prevent
- First and foremost, thoroughly inspect your plants for the presence of aphids after finding initial signs of infestation.
- The mosaic virus, unfortunately, has no cure. The only effective cure is to avoid it in the first place.
- To prevent sick weeds from spreading throughout the garden, make sure to thoroughly weed the planting beds. Always avoid harvesting or planting seeds from infected plants, and keep an eye out for aphids, especially if any of your garden plants are showing symptoms of the virus.
4. Bottom Rot
Some sorts of infestation and illness can be avoided by keeping lettuce leaves away from the soil beneath them. When plants are lying against the ground, pests and soilborne pathogens have better access to your crops.
In garden soil, opportunistic fungi from the Rhizoctonia genus are extremely common, and unfortunately, they thrive in similar conditions to lettuce.
It’s especially aggressive when soil temperatures are consistently between 75 and 80 degrees Fahrenheit.
Keep in mind, though, that some strains can infect other crops, including potatoes, onions, and even weeds, so keep your garden beds thoroughly weeded in between plantings.
How To prevent
- If your plants are affected, you’ll see a brown or rust-like colour on the midribs, which often develops into scabby areas.
- Slimy parts may eventually take over the majority of the bottom of the head or the stems.If the plant is allowed to die, the leaves will droop and yellow, the rust hue will turn black, and the slimy texture will dry to a powder.
- Bottom rot, like many other fungal or bacterial diseases that damage the garden, has no known cure, therefore avoidance is vital.
- When planting, mounding soil can help keep the leaves of head lettuce, in particular, from coming into contact with the ground.
- A basic, mounded row of four to six inches would suffice to elevate heads, and it will also make it simpler to keep leaves from sitting in water that has accumulated on the ground, where the fungus can also be found.
Regardless of whether you’ve experienced a disease outbreak, rotating crops each season is a good idea. When a fungal infection is present, tilling the planting beds deeply before planting can assist.
5. Damping Off
Your young seedlings may fall limp on the soil, and the stems may be dark and withered, indicating that the plant is unable to maintain itself. Seedlings may fail to emerge entirely in some instances.
As previously indicated, fungus gnats may accompany seedlings in this situation, which could be your first clue even before the plants start to die off.
It’s too late if you spot gnats on plant leaves, on the soil surface, or drifting in the air the sprouts.
Fungi that flourish in chilly, wet settings, such as garden soil, induce damping off. While it most usually affects seedlings, it has also been reported to harm adult plants, causing root or crown rot in some cases.
Pathogens are commonly found in store-bought garden soil at the time of purchase. Fungi can grow in humid areas or if the soil is kept excessively damp.
Although lettuce seedlings are quite delicate and can be killed very rapidly when infected, this form of fungus can infect several types of seedlings, not just lettuce.
The failure of seedlings to emerge, the thread-like withering of stems, yellow or brown cotyledons, the appearance of fungus gnats, or white, mould-like formations on the surface of the soil, sometimes around the base of the seedlings, are all symptoms of damping off.
The majority of symptoms will appear between the time of planting and the appearance of the first genuine leaves.
Because any tools or pots that have been exposed to the fungus can potentially propagate the disease to new crops, disinfecting implements or containers that have been exposed before reusing them can be an ideal preventative measure for damping off.
How To prevent
- Tools can be sterilized with rubbing alcohol or bleach; however, chlorine is harmful to metal instruments.
- When planting, use fresh potting soil and heat mats to keep the soil warm, as fungi thrive in cool, moist soil. Control is best achieved at temperatures above 70°F. When watering plants, use room-temperature water as well.
- Consider using a grow lamp to boost available light, which can help plants establish themselves while also warming and drying the soil at the surface, preventing gnats and fungus from settling in. It also helps if there is enough airflow.
Lettuce is rather simple to cultivate, and if you follow proper gardening methods and the advice in this article, you should have no trouble collecting your organic greens.
Have you ever had to deal with any of these lettuce ailments? Please share your thoughts in the comments box below!