Top 10 Grower Issues

Leaf scorch can be caused by many factors in a growing environment, the two main ways leaves are burned is by physical or chemical means:

Physical leaf burn can occur by direct heat whether generated by a weed flamer, heater in the greenhouse, or a prism by high intensity light and a water droplet. Other physical methods of leaf scorch can be caused by insects with piercing and sucking body parts, or plant diseases which leave necrotic spots on leaf tissue to dry out. The best management practices for controlling physical leaf scorch are setting and controlling high intensity lighting or shade of plants in direct sunlight. Managing moisture accumulation on leaf surfaces during light hours. Implementing and maintaining an Integrated Pest Management program to keep insects and plant diseases in check.

Chemical leaf scorches are injury to plants by chemical means, these chemicals can be conventional or organic in origin, and can be applied directly on leaves or through the plant growing media. Salt scald or fertilizer burning of leaves is probably the most prevalent way to burn leaves and flowers. The fertilizer scorch can be compounded by physical leaf burn, especially in a foliar application under high intensity lighting. Other ways to scorch leaves is improper application of insecticides and fungicides. The Best Management Practices to reduce leaf scorch by chemical means is to read and understand the label of any material applied to your crop. Check fertilizer, EC and pH levels regularly to maintain chemical levels safely.

Burning of leaves

Powdery MildewPowdery mildew is a fungal disease affecting plants grown indoors and out, caused by many different species of fungi in the order Erysiphales. Infected plants display white powdery spots on the leaves and stems which reduce the plants ability for photosynthesis, thus reducing growth and yield. Powdery Mildew develops in temperate environments (68°F-76°F) with high humidity (>50%). The best management practices are to use resistant cultivars, reduce the effects of environment variables (Temperature and Humidity), use of chemical controls (Homeopathic (Milk) spray, sulfur, fungicides), and cleanliness of the grow room or greenhouse.

Nutrients left over in the produce impacting the tasteSome growers believe excess fertilizer nutrients can bio-accumulate in plants. As a safeguard for taste and flavor some growers will flush their systems with straight water for a period of time before harvest to reduce these nutrients in plants.

Overdosing and Underdosing of nutrientsFertilizers in general are formulations of salts. Over fertilization of plants can result in physical damage to plants by “salt burn”, where the leaves of the plant are damaged. Salt burn of plant leaves will start around the edges of the leaf, and if not corrected will kill the whole leaf and then the entire plant. Fertilizers in most cases are acid forming, especially nitrogen and phosphorus, and when overdosed can cause the pH of the

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Nutrients left over in the produce impacting the taste

Nutrients left over in the produce impacting the tasteFertilizers in general are formulations of salts. Over fertilization of plants can result in physical damage to plants by “salt burn”, where the leaves of the plant are damaged. Salt burn of plant leaves will start around the edges of the leaf, and if not corrected will kill the whole leaf and then the entire plant. Fertilizers in most cases are acid forming, especially nitrogen and phosphorus, and when overdosed can cause the pH of the solution in the rhizophere to drop to unsafe levels burning the root hairs and inhibiting uptake of water causing plant death. Be sure to check the pH and Electro-conductivity (EC) of any feeding solution before applying to plants. Pay close atten-tion to nutrient levels in plants and check a nutrient guide as nutrient deficiency can also look like over fertilizing depending on the nutrient. Underdosing of nutrients can be detrimental to your plants, by stunting plant growth, loss of yield, and even crop death. Most deficiency symptoms will be a color change to your leaves. Be careful as color changes in plants leaves can mean many different things, and many times are not related to nutrients. Some nutrients are pH dependent for proper uptake, so check your pH often to make sure your plants are receiving all the nutrients from the solution. Please consult a reference guide and tissue sample to ensure you're correcting the right problem.

Some growers believe excess fertilizer nutrients can bio-accumulate in plants. As a safeguard for taste and flavor some growers will flush their systems with straight water for a period of time before harvest to reduce these nutrients in plants.

Compatibility of various nutrientsWhen it comes to the compatibility of nutrients, we answer the question of why 6.5pH is optimal for plant growth. At optimal pH all the nutrients are at their highest availability for plants in relation to each other. Plants require more of some nutrients at different times of their development (Vegetative Vs. Flowering), for this reason we see different formulations of nutrients in fertilizers for particular growth stages. Growers who formulate and mix their own fertilizers need to use caution as the compatibility of the raw ingredients are not always compatible and can cause serious injury to themselves or their equipment if mixed together improperly.

Pest controlPest Control is important to keep plants growing at their optimum, weeds (outdoor), insects, vertebrates, and pathogens will pop up from time to time. In outdoor growing, weeds and large vertebrates (voles, rats, rabbits, deer and other animals) are bound to come and damage plants if not excluded or removed from growing areas. Other pests, including diseases and insects will damage plants in both indoor and outdoor growing environments. Disease management is best when prevented by site selection, plant health, moisture control, and site cleanliness. Although the use of chemical based sprays will control many pathogens, prevention is key to successful growing. Damaging insect populations such as aphids, mites, and white fly can quickly bring down a growing operation if left unchecked. The use of an Integrated Pest Management(IPM) program will keep most insects at bay. IPM uses beneficial insects (Lady Beetles, Lace Wings, Persimilis) to control populations of plant damaging insects, and increases the amount and type of control measures until the problem pests are controlled.

Moisture ControlHumidity is actually a measure of how much water vapor is being “held” in the air. There are different ways to measure humidity, including "absolute," "specific," or "relative" humidity. Relative Humidity (RH) is the measure growers use to determine the humidity levels. Plants at different growth stages will require different humidity levels for optimum growth. Seedlings and clones require higher RH of 70-80% until root systems have matured. Vegetative plants need a RH of 40-70% and flowering plants need a RH of 40-50%. Use ventilation and air circulation or even a dehumidifier to keep plants dry, droplet development on leaves might lead to fungal infections of leaves and flowers. Low levels of humidity (<25%) can lead to growth problems, as leaf stomata close to conserve water from leaving the plant and constrict the amount of carbon dioxide available to the plant. High levels of humidity (>70%) can also lead to nutrient problems as water vapor will not move from the plant to the atmosphere reducing the ability of plants to uptake nutrients.

Water retention capacity in the media

The type of media used for your plants is an important decision, whether using soil, clay stones, coco, rock wool. The type of media and/or its composition (percentage of components mixed) will determine the effective water retention capacity. Typically, the larger the pores a material has, the less water retention capacity. This is due to surface area, smaller pores contain more surface area to hold water. The amount of water retention will help to dictate watering schedules in con-junction with temperature, humidity, and plant size, but must also consider the amount of oxygen allowed to contact the roots. Deciding to use a media for water retention must be predicated on all the factors of the grow environment to have the best results.

Transpiration rateWater is necessary for plant growth but only <3% of water is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation. Transpiration is the process of water movement through a plant and its evaporation from leaf stomates, flowers, and stems to the atmosphere. Although there are other drivers of water movement in plants such as Mass Flow by capillary action and cohesion and tension, the main driver of water movement in plants is by a pressure gradiant between the leaf surface and the atmosphere. In short, as water leaves the plant to the atmosphere there is a vaccum pulling water up the plant. As the atmosphere becomes drier, the pressure gradiant pulls more water from the leaf surface, and as the atmosphere becomes more humid less water is pulled from the leaves. In order to regulate the amount of water moving through plants, specialized cells called stomata open and close to regulate water loss or gain, but at some point regarless of the pressure differential the stomata must open to allow for movement of gases (Carbon Dioxide and Oxygen) in and out of plants. Carbon Dioxide being the key building block for photosynthesis, the process where light energy and Carbon Dioxide converted to sugars essential to plant growth..

Branch width and strengthPlant architecture is determined by two dominate factors, nature and nurture. Where Nature has set the genetics of plants to develop in a particular manner, and the nurture of plants determines the potential of those plants. Some genetics will determine whether one variety can support itself or needs help by pruning, training, and grow technique (sea of green, lollipopping, super crop-ping). Another way to increase branch strength is through fertilization, silica and calcium are two nutrients which help to strengthen cell walls and provide strength for developing plants.

SterilizingWIndoor grow rooms and greenhouses should be sterile before you start growing plants, but it’s also important not to get carried away. One teaspoon of bleach to a gallon of water will be an effective sterilizer. Clean the floors, walls, and vents before equipment is set up, then sterilize the equipment: pots, flats, and anything else. Re-sterilize any tool or piece of equipment as used or reused during a grow cycle, especially pruning shears when moved from one plant to another to prevent the spreading of disease and pathogens.Once the room has been sterilized and cleaned with the mild bleach solution, allow it to completely air dry before setting up plants. In addition to keeping your grow room clean, you also need to remember to keep yourself clean. Shower to remove any insects (mites etc), fungal spores, or bacteria you might be carrying, but most importantly remember to change your clothes. Ideally you should have one or two sets of clothes that are used for the grow room only, to prevent anything from outside entering the roomGeneral CleanlinessGrow rooms and greenhouses can become unkempt, and this can cause enormous damage to your plants.

Here are five helpful tips:

• Arrange pots in neat, tidy rows. Equal spacing gives all plants equal access to light and air.

• Use trays under all pots. The trays will collect excess moisture from the plants, keeping it off the floor and easy to remove from the space ensuring humidity levels don’t rise too high.

• Clean spills immediately, if there is overflow or a spill of water on the floor, clean it up immediately. Leaving it to sit will negatively impact humidity levels, encouraging mold and bacteria to grow.

• Prune your plants and remove dead leaves. Dead and dying leaves decay, prevent good future plant growth, and can also be a breeding ground for pathogens. Clean up any leaves which have fallen off to keep your plants healthy and thriving.

• Use a HEPA filter over your air intake vent. This will ensure that no pests enter the room from outside