Our good friend Marco Antonio Reñé Prat established himself as a cannabis activist in Spain in the 1990s, writing for Cañamo magazine and founder of one of the first grow shops in Spain.
The author of Cultivar Marihuana, we asked him for some expert advice on common pests and diseases Mediterranean growers face:
Growing cannabis in the Mediterranean
The Mediterranean climate is characterized by warm temperatures and generally high humidity, both of which favor the appearance of pests and diseases. The relationship between pests and diseases and environmental conditions is very important and outdoor cultivation is more difficult to control for this reason. Cannabis is a very attractive plant for pests and diseases. Here we look at some of the most important.
Enemy Number 1 – Red Spider Mite
(Tetranychus urticae and Tetranychus cinnabarinus are the most common representatives of this species). The red spider mite attacks all kinds of crops. Approximately half a millimeter in size, it has a very fast and large egg production and a faster reproductive cycle if weather conditions are favorable. The number one enemy of inexperienced growers as well as experts. Its impact is usually devastating due to late detection of the pest. As it has resistance to many z in the médium stage, it is important to always use biological solutions for treatment.
Detection: Often growers will discover them too late. Get into the habit of checking the undersides of leaves (where they suck sap to the plant). Look for very small white dots on the upper surface of leaves, a sign that it has been sucked from underneath.
Enemy Number 2 – White Fly
From the Aleyrodidae family. These are tiny white winged insects, approximately 2 mm in size. Their proliferation is very fast, and can cause great damage to all crops. They are sucking insects, so leave wounds in the plant which become the focus for new infections. At the same time, like aphids, they secrete honeydew that can attract other diseases. If the plant is in blooming phase, buds can be spoiled by secretions.
Detection: Although its flying characteristic makes them more easily detectable, for early detection, chromatic traps are a very good choice.
Enemy Number 3 – Caterpillars
(Spodotera Exigua and Spodotera Litoralis) This is one of the most rapacious and destructive pests, especially in outdoor crops. The most damaging is the armyworm (which develops into an armyworm moth). It travels up the stem, biting the base of the bud to extract plant sap. It can cause enormous damage to the plant and provoke other diseases such as botrytis.
Detection: Damage is usually observed in the form of observing the damage to the plant, leaves bites, broken buds. Also check for droppings (which can also be a source of contamination).
Enemy Number 4 – Powdery Mildew
Yeast infections are feared by all growers, since the proliferation of these organisms is very fast. Powdery mildew is a fungus that usually appears as a thin layer or cottony ash, on top of leaves and also extends to the buds. This causes serious damage and can sometimes ruin almost the entire crop. It is highly influenced by high humidity and insufficient ventilation.
Detection: Be attentive to the leaves, especially more bushy areas of the plant. Choose your variety well too as some (such as big bud indicas) are more susceptible. The best prevention is always a healthy and strong plant.
Enemy Number 5 – Botrytis (Bud Rot)
This is also a widespread fungus that can cause devastating damage, and is also caused by high humidity. It is very easily detected by observing rotted brown buds. As in the case of powdery mildew, contaminated buds are inappropriate for consumption.
Detection: Once it appears it is very difficult to combat, so be vigilant (especially in flowering stages when humidity is high). The best récipe for preventing Botrytis is to breed a healthy and robust plant.
The key to preventing pests and disease is:
1) Keep our plants as healthy and strong as possible.
2) Keep the grow space clean – remove remains of dry leaves and gathered dirt because they attract pathogens.
3) Observation and close monitoring of our plants is always the best tool to fight pests. Early detection of the problem is the easiest way to eradicate it.