{"id":7137,"date":"2023-06-28T10:56:55","date_gmt":"2023-06-28T08:56:55","guid":{"rendered":"https:\/\/marijuanagrowing.com\/?p=7137"},"modified":"2024-02-06T14:16:09","modified_gmt":"2024-02-06T13:16:09","slug":"diseases-pests-problems","status":"publish","type":"post","link":"https:\/\/marijuanagrowing.com\/diseases-pests-problems\/","title":{"rendered":"Diseases, Pests & Problems – Chapter 8"},"content":{"rendered":"\n
Cleanliness is the secret to disease and pest prevention. Keep the floor, ground, and substrate surface clean. Dirty tools often carry microscopic pests and diseases. Wearing clean clothes and using clean tools will reduce problems. A separate set of indoor tools is easy to keep clean.<\/p>\n\n\n\n
Wash your hands if you touch diseased plants. Pay attention to simple hygiene. Do not work in the dirty outdoor garden and then visit the indoor garden. Even walking across a lawn or brushing up against outdoor plants could carry pests and diseases to your indoor garden. Stay away from dogs, cats, and other pets that have been outdoors, and don\u2019t let them in the garden. Houseplants can also help spread pests and disease.<\/p>\n\n\n\n
Keep all debris off the floor. Clean the garden area regularly.<\/p>\n\n\n\n
Dip tools in alcohol to disinfect.<\/p>\n\n\n\n
Wash your hands to avoid transmitting insects and diseases from other plants.<\/p>\n\n\n\n
Grow insect- and fungus-resistant strains like Power Plant and keep the garden strong and healthy. Keep air well-circulated and fresh. Keep humidity around 50% and maintain the temperature at about 75\u00b0F (24\u00b0C) during the day and about 5\u00b0F (3\u00b0C) cooler at night.<\/p>\n\n\n\n
Keep the temperature and humidity at the proper levels to avoid cultural, pest, and disease problems.<\/p>\n\n\n\n
Make sure there is plenty of ventilation and air circulation.<\/p>\n\n\n\n
Avoid most common ailments <\/strong>by keeping light, temperature, and humidity at the proper levels. Use clean water, the proper complete nutrient solution, maintain EC and pH at the correct levels, and change the nutrient solution every week. Fine-tune these vital factors before deciding that plants are nutrient deficient.<\/p>\n\n\n\n Many problems in containerized gardens <\/strong>and to a lesser degree outdoor gardens, are misdiagnosed as a lack or excess of fertilizer. Inexperienced growers tend to solve nutrient concerns by adding fertilizer rather than learning the cause of the problem and solving it. Often, adding more fertilizer compounds and complicates cultivation problems.<\/p>\n\n\n\n Once a plant demonstrates symptoms, <\/strong>it has already undergone stress. It will take time for it to resume vigorous growth. Correct identification of each symptom as soon as it occurs is essential to help plants retain vigor. Indoor, greenhouse and some outdoor marijuana crops live a short three or four months and are harvested so fast that plants do not have time to recover from nutrient imbalances. One small imbalance could retard growth by a week or more and diminish harvest.<\/p>\n\n\n\n Light <\/strong>is often a problem indoors. Low levels of light and light of the wrong color spectrum causes slow growth. When growth is slow, diseases and pests tend to attack weaker plants. Nutrient deficiencies and excesses also tend to develop quickly.<\/p>\n\n\n\n Indoors, the proper LED <\/strong>lights supply the perfect spectrum and intensity for cannabis growth. Mounting height of the light fixture and even coverage of intense light are essential. Check with light manufacturers for mounting height and light coverage.<\/p>\n\n\n\n Too much light <\/strong>is seldom a problem. Intense light from HID lights radiates a good deal of heat. When mounted at the proper height the light footprint spreads evenly.<\/p>\n\n\n\n Air temperature and humidity <\/strong>also influence growth. Keep the temperature in the range of 70\u00b0\u201375\u00b0F (21\u00b0\u201324\u00b0C) day and about 65\u00b0\u201370\u00b0F (18\u00b0\u201321\u00b0C) night. Keep relative humidity 55\u201365% vegetative room and 50% flowering room. The humidity climbs at night when the lights go out and temperatures drop. Typically, venting moist air out of the room will keep humidity in the proper range.<\/p>\n\n\n\n Circulation fans <\/strong>keep the air from stratifying, hot air rises and cooler air lays near the ground. Circulating air moves foliage and creates a more difficult to attack plant.<\/p>\n\n\n\n Ventilation fans <\/strong>keep air changing in the grow room. Control heat and humidity with ventilation. Turn the ventilation fan on to evacuate hot humid air. New fresh air will replace old stale air to keep plants healthy.<\/p>\n\n\n\n Water quality <\/strong>\u2013 Raw input water with a dissolved salt reading greater than 300 ppm is often treated with a Reverse Osmosis (RO) device to remove the excess salts. RO-treated water is ideal because it has virtually no dissolved salts. You add all the nutrient salts to form a perfect nutrient solution. RO devices also remove sodium from the water. Excess sodium (more than 50 ppm) in the water supply restricts water and nutrients from being absorbed by the roots.<\/p>\n\n\n\n Over-watering <\/strong>is a common problem. Too often gardeners kill containerized plants with kindness, too much water and often fertilizer. Use a moisture meter with a probe to check substrate moisture levels.<\/p>\n\n\n\n Underwatering occurs when the substrate is not completely wet. Water never reaches the dry substrate. A moisture meter will help avoid under-watering and help you find dry soil pockets that do not get watered in the container.<\/p>\n\n\n\n An imbalanced pH <\/strong>causes problems. The pH of input water can be about 7.0 because fertilizers are acidic and drop the pH of the final nutrient solution. Keep the pH adjusted in the range of 5.5\u20136.5, in hydroponics, and 6\u20136.5 in soil gardens to allow nutrients to be chemically available.<\/p>\n\n\n\n The optimum pH range <\/strong>for cannabis growth is 5.8- 6.2. But cannabis plants will grow within a pH range of 5.5-6.5. Within this range, nutrients are chemically available in solution; above or below this range, several nutrients become less available. And, different substrates, coco coir, rockwool, soilless mix, expanded clay pellets, all have specific air and moisture needs to ensure nutrients are available. In soil, a pH below 6.5 may cause a deficiency in calcium, which causes root tips to burn and leaves become subject to fungal infections and dead spots on foliage. A pH above 7.0 could slow down the plant’s iron intake and result in chlorotic leaves causing veins to yellow. Adding more calcium and iron will not solve the problems.<\/p>\n\n\n\n Nutrient deficiencies and excesses can also be confused with disease and pest damage. For example, Hemp Russet mites cause slow growth and small deformed flower growth. Inexperienced growers may confuse this with a nutrient problem.<\/strong><\/p>\n\n\n\n Over-fertilizing <\/strong>is common. Adding too much fertilizer without sufficient runoff causes nutrient salts to build up in the substrate, creating toxic conditions. Nutrient excesses and nutrient deficiencies occur that are caused by toxic levels of fertilizer in the substrate.<\/p>\n\n\n\n Under-fertilizing <\/strong>is less common. But using the wrong measuring scale\/container or misinterpreting the mixing formula is somewhat common. Always double check the proportions of nutrients to be mixed into solution.<\/p>\n\n\n\n Poor drainage, <\/strong>cold, soggy soil impairs nutrient uptake and leads to root rot. Tell tale signs of these conditions include weak, supple, discolored, and super green foliage.<\/p>\n\n\n\n Soil temperature <\/strong>should be kept below 65\u00baF (18\u00baC) so that nutrients are readily available for uptake. Hot soil impairs nutrient uptake by roots and causes excessive water consumption. Outward signs include discolored foliage, dry foliage and hot soil.<\/p>\n\n\n\n Damage from cultural practices<\/strong><\/p>\n\n\n\nCultural Practice<\/td> Symptom<\/td><\/tr> Lack of light<\/td> slow, spindly growth and stretching between internodes<\/td><\/tr> Light burn<\/td> burned patches on leaves<\/td><\/tr> Lack of ventilation to the plant<\/td> slow growth and curled-down leaves<\/td><\/tr> High humidity<\/td> slow growth and curled-down leaves<\/td><\/tr> Low humidity<\/td> seldom a problem and plants use more water<\/td><\/tr> High temperature<\/td> slow growth and drooping leaves<\/td><\/tr> Low temperature<\/td> slow growth, purpling, and no flowers<\/td><\/tr> Over-watering<\/td> slow growth, disease and nutrient deficiencies<\/td><\/tr> Under-watering<\/td> wilting, slow growth, disease and nutrient deficiencies<\/td><\/tr> Nutrient pH<\/td> slow growth, poor nutrient uptake, discolored foliage<\/td><\/tr> Nutrient overdose<\/td> slow growth, dry foliage, burned and discolored foliage<\/td><\/tr> Soil has nutrient buildup<\/td> slow growth, burned and discolored foliage<\/td><\/tr> Poor drainage<\/td> slow growth, curled down leaves<\/td><\/tr> Indoor air pollution<\/td> slow growth and sickly appearance<\/td><\/tr> Spray application damage<\/td> burned spots<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Nutrient Deficiencies & Excesses<\/h2>\n\n\n