THE MAIN PROBLEMS THAT WE ARE GOING TO FIND IN THE CULTIVATION OF LETTUCE
We continue to add one more file to our database of crop pests and diseases . Now we are giving way to a very important crop in most of the world, lettuce. This crop is plagued by numerous insects, fungi and bacteria that deteriorate and alter the leaves of this vegetable. We are going to learn to distinguish each problem and to solve it.
Before starting with the “heart” of the matter, it is interesting to know some peculiarities of the cultivation of lettuce . In the previous link we offer you some important things about its cultivation.
The climatic characteristics, the soil, the irrigation and fertilizer and other interesting data to start with the lettuce in our garden.
GRAY WORM ( AGROTIS SP. )
The gray worm affects a wide variety of plants, including potatoes, beets, asparagus, crucifers, etc.
It is usually attracted to cool and humid areas such as those provided by growing lettuce. At night they feed on the leaves and during the day they hide under the ground.
MINERS ( LIRIOMYZA TRIFOLII )
Inside the lettuce leaf, the larva burrows galleries while feeding on the parenchymal tissue. This pest pays special attention to the beginning of the plantation, delaying the start of maturation or even rejecting the commercial product.
WHITEFLY ( TRIALEURODES VAPORARIORUM )
The whitefly is highly polyphagic and attacks a wide variety of crops. The damage occurs when it feeds on the sap of the plant, causing yellowing of these and their subsequent weakening. At the same time they produce molasses and attract infection by the “bold” fungus.
Another of the great problems of the whitefly is that it is a carrier of virus that has no treatment and can end up with the culture in a short period of time.
THRIPS ( FRANKLINIELLA OCCIDENTALIS )
Thrips is an insect that is present in a large number of crops and one of the ones that is causing the most problems.
The symptoms in lettuce appear after the bite of the trip on the leaf. The level of damage to the crop depends on the population and the number of bites. However, the most problematic thing about Frankliniella occidentalis is its ability to carry numerous viruses, including tomato browning virus (TSWV).
ALTERNARIA ( ALTERNARIA DAUCI – STEMPHYLLIUM SPP.)
When it comes to recognizing this disease caused by a fungus, it is necessary to detect small dark spots on the lettuce leaves. It usually develops in high humidity conditions, which is why it is sometimes used preventively when there are rainy seasons.
ANTHRACNOSE ( MICRODOCHIUM PANATTONIANA )
It usually appears on the oldest leaves before the rest of the leaves, with a special predominance by the central nerve, petiole and blade.
Small, sunken, yellowish spots appear on these leaves with a reddish or necrotic margin. Over time, this reddish ring spreads inwards, necrotizing the entire stain.
POWDERY MILDEW ( ERYSIPHE CICHORACERUM )
Powdery mildew is a well-known fungal disease that is widespread in almost all crops. It usually develops both on the upper side and on the underside of the leaf, the outer leaves being covered with a whitish powdery mycelium .
It usually appears when the climate is not very humid (relative humidity around 70%) and when there is no rainy season.
GRAY ROT ( BOTRYTIS CINEREA)
This fungus can appear in any vegetative phase of the lettuce crop. Usually it is associated with excess humidity, so irrigation control is very important. Aeration is also a good technique to prevent the spread of this disease.
The attack usually begins at the base of the lettuce, although it can also appear on leaves that have wounds, problems or pathophysiologies.
SEPTORIA ( SEPTORIA LACTUCAE )
Septoria produces spots on the underside of the leaves. For this fungus to make its appearance, the crop must be in areas of high humidity or in the rainy season.
Small, irregularly shaped chlorotic spots appear on the leaves. Over time, these spots become necrotic and a chlorotic ring forms around it, a symptom of the progress of the disease.
MILDEW ( BREMIA LACTUCAE)
SCLEROTINIA ( SCLEROTINA SCLEROTIORUM )
This disease causes the appearance of white, soft-looking rots on the lettuce leaves. The infection begins in the basal part of the plant and spreads over time. This fungus can remain in the soil for up to 5 years, so cleaning techniques such as solarization are recommended .