Tipburn in Hydroponic Lettuce
By: Dan Gillespie, Technical Specialist
Tipburn is among the most common issues experienced in controlled environment lettuce production. Tipburn occurs as browning of the edges or tips of new young leaves (Figure 1).
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| Figure 1. Tipburn on young lettuce leaves |
Tipburn in lettuce is most often caused by calcium deficiency. However, this deficiencyis usually not a result of insufficient calcium in the nutrient solution. To understand why tip burn occurs (and how to avoid it), we need to understand how calcium travels through the plant
Calcium moves through the plant differently than nearly all other nutrients: It requires mass flow of water. Think of it as a hose that must be turned on for the calcium to move into the plant. Mass flow is driven by transpiration, so high transpiration rates will enhance calcium uptake and translocation, whereas, low transpiration rates will decrease calcium uptake and translocation. When a head of lettuce grows, the growing point becomes enclosed by older mature leaves, creating a high humidity microclimate. This microclimate results in decreased transpiration, which leads to the tip burn.
The first step in preventing tipburn is ensuring that calcium is not lacking in the nutrient solution and that your fertilizer formula has a proper ratio of potassium, calcium, and magnesium. Source water with calcium concentration above 40 ppm is typically a good candidate for one-part fertilizer systems such as Jack’s Nutrients 12-4-16 RO or Jack’s Nutrients 15-5-20 Tap. However, source water with lower concentrations of calcium will typically require the use of a two-part fertilizer system, such as Jack’s Nutrients Part A 12-4-26 and Cal Nit Part B 15-0-0. Additionally, nutrient solution electrical conductivity should generally not exceed 2.5 mS/cm, as high soluble salt levels will decrease water and calcium uptake. Note that all Jack’s Nutrients provide the proper balance of nutrients.
As stated above, even when calcium levels in the nutrient solution are adequate, tipburn may still occur. Improve airflow around the growing tip with the use of vertical airflow fans.Vertical airflow should provide just enough air movement to gently move plant leaves (0.3-0.5 m/sec). This will eliminate the microclimate and facilitate calcium uptake.
If vertical airflow fans cannot be installed, another option to prevent tipburn is increasing night time humidity above 95%. High nighttime humidity leads to increased root pressure, and thus, increases water and calcium translocation to the growing point of the plant. However, this strategy can increase the threat of fungal diseases that thrive in high humidity environments.
| Product Name | Item Number | |
|---|---|---|
| Jack's Nutirents 12-4-16 RO | 33-12416 | |
| Jack's Nutirents 15-5-20 Tap | 33-15520 | |
| Jack's Nutirents 5-12-26 FeED Part A | 33-51226 | |
| Jack's Nutirents 15-0-0 Boost Cal Nit Part B | 33-79080 |
Using Sticky Cards for Insect Monitoring
By: GGSPro Technical Specialists
Sticky cards are the best monitoring tool available for flying insects, such as thrips, fungus gnat adults, shorefly adults, whiteflies and winged aphids. Using cards for active monitoring of these pests supports proactive decision making for best management of pest populations.
Sticky cards are available in solid yellow, solid blue, and bi-colored forms (two-sided, yellow on one side and blue on the other). Some sticky cards are pre-printed with a grid pattern that allows for quicker counting. Sticky cards come with a protective sheet that is removed to expose the sticky surface. To make these easier to work with, take a tip from the pros and keep your sticky cards refrigerated until use.
Proper use of the cards will generate the best data. Prior to placing cards in the crop, date and number each card with a consistent location code. Sticky cards should be placed above the crop with one third of the card in the canopy. Additionally, place some cards vertically just above the crop canopy; avoid placing sticky cards too high above foliage to ensure you pick up all flying insects. To monitor for insects emerging from the media (e.g. thrips and fungus gnats), place yellow sticky cards horizontally just above the media surface. Growers generally use 1-2 cards per 1000 square feet, increasing to 3-4 cards per 1000 square feet when monitoring for thrips or when monitoring higher value crops. Remember to place additional sticky cards near doors, vents or areas of concern.
Speaking of beneficials, when releasing Aphidius, Encarsia, Eretmocerus or Orius, take cards down on the day of release to minimize capture of the good bugs. Return the cards to the crop a few days after release.
| Product | Item Number | |
|---|---|---|
| 2-color blue/yellow sticky cards, 4"x5"; 10 per pack | 74-3668 | |
| Yellow moisture resistant monitoring cards, 3"x5"; 50 per pack | 74-36705 | |
| Trapline T Yellow Roller trap 6"x328' | SB8051-05 | |
| Sticky yellow trap roll 12"x300' | 74-12300 | |
| Sticky yellow trap roll 6"x1500' | 74-61500 | |
| Sticky blue trap roll 6"x1500' | 74-61500B |
Controlling Water Flow
Written by: Kurt Becker, Dramm CorporationYou may have heard that the most important person on a cultivation team is the person with the hose in their hand. Proper irrigation can make or break a crop. One challenge is to ensure that proper flow and pressure to address different needs. This is complicated by the fact that crop needs change dramatically over a short period of time. How do you help your team meet these changing needs? You give them the right watering tools!
Dramm produces a full assortment of professional watering tools, including water breakers. These specialized nozzles break the water into smaller droplets and streams, simulating rain, which softens impact on plants and media while absorbing and providing needed oxygen to the roots. Different water breakers tailor the delivery pattern, flow and volume for specific containers, media and plant stages. In addition to the essential, high-flow 400 series, Dramm manufactures innovative, specialized water breakers to meet all irrigation needs.
The 1000PL Series.
Starting with the original Redhead, the 1000PL uses 1000 smaller holes in a stainless steel disk. This allows for a softer pattern for younger plants along with the ability to throttle the flow while still keeping a pattern. Now, the 1000PLs are available in Narrow, Medium and Wide versions offering different amounts of water per square inch of coverage.
750PL
The 750PL reduces the flow even further. Using the same size hole as the 1000PL, but using fewer holes, the 750PL applies less water. This allows for lighter watering when required. The 750PL throws a wide pattern for less water per square inch of coverage.
Fan Nozzle
Most fan nozzles are consumer tools and have uneven patterns. Dramm’s Commercial Fan Nozzle was developed to offer a precise, rectangular pattern that allows for medium to very low flow while still producing even streams.
350PL Screen-Aire
The 350 lands at the opposite end of the spectrum, delivering a very high flow rate with a soft, aerated pattern. Water exits the nozzle like a kitchen faucet, a single stream full of air bubbles. This allows for a lot of water without disturbing soil or top-dressed fertilizers. Great for quick watering of containers. The 350 is also perfect for rewetting dry media, as the bubbles hold the water on the surface of the media longer.
Valves
Remember to match the valve to the nozzle to allow precise control of flow rate. Valve operation is important to note. Does the watering require on-off operation or is it turn on and go? The OneTouch and OneTouch HighFlow offer easy control of the flow. Other valves, like the 300 Brass Shut-Off are high flow, quarter turn valves for quick watering.
| Description | Item Number | |
|---|---|---|
| 80170002 | ||
| 33-6101 | ||
| 41-600101 | ||
| 33-350PLC | ||
| 33-5234 | ||
| 33-5233 | ||
| 33-5237 | ||
| 33-5236 | ||
| 33-2079 | ||
| 33-5235 | ||
| 33-610F | ||
| 33-5327 | ||
| 41-400300 | ||
| 33-51051 | ||
| 44-5607 | ||
| 33-14700 | ||
| 33-5365 |
Punch Out Powdery Mildew On Cannabis
Powdery mildew (PM) is made up of many fungal pathogen species that attack and thrive off healthy, living plant tissue. Golovinomyces sp. (aka Erysiphe sp.) is the most common PM species that growers find on cannabis today. We recognize PM as producing a distinctive white sporulation on the foliage that looks like powdered sugar. Without proper management through chemical and cultural practices, this pathogen can quickly spread throughout your operation and decrease crop quality. |
| Powdery mildew forms white spores on the surface of the foliage. |
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| Powdery mildew should not be mistaken for trichome production |
areas between crops. Following physical removal of debris, the first step is to clean all hard surfaces using a cleaning product such as Strip-It (for greenhouses) or Horti-Klor (for warehouses)*. Once surfaces have been cleaned, use a sanitizing agent such as KleenGrow (rinse direct crop contact surfaces with potable water), ZeroTol 2.0 or SaniDate 5.0 for disinfection purposes*. It is critical to ensure that all cuttings and clones coming into a new production area are free of disease. Immediately remove any infected foliage and dispose of it properly. Replace gloves and other protective equipment after handling infected material. Work in infected areas late in the day and avoid staff moving back into clean areas from infected areas.
EPA registered and 25(b) products need to be approved for use on cannabis by the regulatory agency in the state in which the product would be used. When using biofungicides, best practices call for application of ZeroTol 2.0 before Cease or Triathlon BA to destroy surface spores of the pathogen on contact while the biofungicide protects uninfected tissue. Contact your Griffin sales person or GGSPro for product rates and application intervals.
| Product Name | Item Number | ||
|---|---|---|---|
| 25(b) Products | |||
| Procidic 2 | 71-2742 | ||
| EPA Registered Products | |||
| Cease | 71-13301 | ||
| Companion | 71-1375 | ||
| Horti-Klor | 74-2105 | ||
| KleenGrow | 74-21101 | ||
| MilStop | 71-2879B | ||
| Regalia CG | 70-2841 | ||
| SaniDate 5.0 | 71-35001 | ||
| Sil-Matrix | 71-2940 | ||
| Strip-It Pro | 74-2125 | ||
| Triathlon BA | 71-3040 | ||
| ZeroTol 2.0 | 71-35501 | ||
*Check state approval status for these products.
Getting More From Your Cleaners and Sanitizers With Foam
All food and medicinal crop growers take great care to keep their production spaces clean. Often, this process involves a full sanitation protocol for the production space at the end of a crop cycle to reduce the risk of carryover pests and pathogens. The complete process involves four steps: Physical cleaning (remove the debris), chemical cleaning, rinsing with clear water and sanitizing.It’s important to include the physical and chemical cleaning steps in the process prior to sanitizing. Favorite sanitizers, including ZeroTol 2.0, SaniDate 5.0 and Kleengrow, treat the surfaces they contact. If the surface is dirty, the sanitizers will treat the debris, but not penetrate to the surface below. If the sanitizer can’t contact the surface, the surface can’t get clean!
We can all increase the efficacy of our cleaners and sanitizers by utilizing the power of foam. Foaming makes the application more effective by increasing coverage and contact time. Foams also make it a lot easier to see where treatments have been applied.
Griffin offers two great foamers from Dramm to get this job done. With both small and large volume options, growers can have the right tools for all needs, from large greenhouses spaces to smaller warehouse production rooms. The Foam8L is a 5 liter compression foamer that is highly portable and great for small spaces. Expect to treat 400-500 sq ft from one full tank. For larger spaces, turn to the FM20-30 foamer. This cart unit has a 20 gallon tank, a 30 foot hose and runs on compressed air*. Both products are compatible with popular cleaners and sanitizers.
Ask your Griffin sales person for a bulletin outlining GGSPro’s recommendations for hard surface sanitation for food and medicinal crops. Your sales person can help you choose the right cleaner and sanitizer for your situation and will let you know if you need to add a foaming agent to the tank
*Compressed air source required for the FM20-30 Foamer
Boosting Root Development in Cannabis Crops
Cannabis growers are a diverse group. Some grow hemp, others grow marijuana. Some produce organic crops, others use conventional products. But, all cannabis growers have one thing in common: They need healthy roots as quickly as possible.
Proper moisture management is the key to good root growth. Early in propagation, maintain high humidity around seeds and cuttings without adding moisture to the media, which should be wet but not saturated. As roots develop, careful irrigation maintains even media in the wet to moist state. Once roots reach the bottom of the cells, allow the media to dry to the lower end of moist, widening the moisture cycle as the roots continue to develop. Media should never be allowed to reach a dry stage during propagation.
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| Essential Plus 1-0-1 |
To boost root development, Griffin’s GGSPro technical team encourages cannabis growers to utilize Essential 1-0-1. Essential 1-0-1 is a liquid, nutritional supplement containing humic acid, yucca (natural wetting agent) and amino acids in a solution with a very low nutritional charge. This OMRI-listed, organic product has no pesticidal activity or claims, which means it is universally acceptable for use on cannabis. Essential 1-0-1 has a proven track record of speeding and increasing root growth in a wide variety of crops, and we are seeing the same thing in cannabis. Cultivators report stronger root growth and positive impacts on secondary compounds. Apply once as roots start to develop in propagation and again at transplant at 32 oz/100 gal. Many growers realized benefits when repeating application every four weeks throughout the crop. Essential 1-0-1 is compatible with most water-soluble fertilizers, which means you can blend it in your concentrated stock tanks and inject right along with your fertilizer. Or, mix it at final rate in your batch reservoirs.
Add Essential 1-0-1 to your SOP, watch your moisture levels and build roots more quickly for ongoing crop health.
Featured products
Planning to purchase a larger number of containers of Essential 1-0-1? Ask about volume discounts.
Hemp Russet Mites: Scouting and Control Tips
Hemp Russet Mite (HRM) is an eriophyid mite that can severely damage flowers and decrease THC and CBD in cannabis production. Eriophyid mites are small, cigar-shaped pests; they’re capable of reproducing profusely. They infest many horticultural crops.The eriophyid mite that occurs in cannabis is called Aculops cannabicola. It’s known to occur on cannabis, as well as hops and hackberry.
HRM can infest indoor production facilities throughout the year. These mites are carried on incoming plant material, on staff and tools. They can also move readily on wind currents.
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| Hemp Russet Mites on cannabis |
HRM scouting tips
HRM detection should be part of the weekly scouting protocol that goes with yellow sticky card and whole-plant inspections. HRM should be addressed as quickly as possible.
When scouting, growers should look for leaf curling and carefully inspect leaves with a 20X hand lens or greater magnification. Scout crop edges and, since HRM are known to spread on wind currents, look near fans, too.
Inward leaf curling is another sign of infestation. If leaf curling is observed, sample the leaves and look in the nooks and crannies of the leaves for HRM.
HRM control options
Control options in cannabis are limited. Beneficial insects are a great option for early HRM infestations, but they’re not known to completely eradicate HRM populations. Release BCAs preventively for best control of HRM.
Horticultural oil sprays are effective at reducing populations. Applicators must read and follow the label instructions, and also follow all state and local regulations regarding chemical application to cannabis crops. All products listed below may not be approved for use in all states. Products other than those listed may be safe, effective and legal.
Featured products
| Product Name | Item Number | |
|---|---|---|
| Ecotec Plus 17% | 70-1507 | |
| SuffOil-X Spray Oil 80% | 70-4040 | |
| Amblyseius andersoni | 30AI2H | |
| Amblyseius andersoni | SB0016-50 | |
| Anderline aa | SB0016-02 | |
| Anderline aa | SB0016-31 | |
| Amblyline cal | SB0013-31 | |
| Californiline | SB0013-01 |
Tech Tip Articles
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April 2020
Tipburn in Hydroponic Lettuce
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April 2020
Using Sticky Cards for Insect Monitoring
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February 2020
Controlling Water Flow
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August 2019
Punch Out Powdery Mildew On Cannabis
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July 2019
Getting More From Your Cleaners and Sanitizers With Foam
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June 2019
Boosting Root Development in Cannabis Crops
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April 2019
Hemp Russet Mites: Scouting and Control Tips