Forcing hydrangeas for Easter? Our friend Dr. Brian Whipker at North Carolina State University has released a great resource on managing nutrients to ensure your blooms are blue and not bluish-purple. Continue reading “Hydrangeas: Getting the (right colour) blues”
If you’re producing poinsettias this year, you are probably just about finished with potting up your newly rooted cuttings. Keeping an eye on your crop throughout the production cycle will help to identify problems early, and allow you to correct the problem before it gets out-of-hand. Consider this blog post your “cheat sheet” on identifying poinsettia nutrition related disorders. Continue reading “Now’s the time to be proactive about poinsettia nutrition”
As we start to move into fall and winter flower crop production cycles, it’s a good time to go back through some basics about nutrient deficiencies.
No matter where you are in a cropping cycle, nutrition problems can be tricky to figure out. The good thing is they can be differentiated from disease or pest issues based on a few key observations:
- If the damage is uniform and crop wide, it’s most likely a nutritional issue
- If the damage is localized or more random, it’s most likely a disease or pest issue
By Sarah Jandricic and Chevonne Carlow
It’s that time of year again, when baskets of Million Bells (Calibrachoa) are going up in the greenhouse. Here’s how to deal with and prevent some of their most common issues.
From a nutritional standpoint, the best thing you can is keep the pH of your calibrachoa in its ideal range; between 5.5 and 6.0. A pH higher than this can inhibit nutrient uptake, especially micronutrients such as iron.
Iron deficiency can be difficult to distinguish from other issues (like Black Root Rot – see below), but typically leads to yellowing of new growth. Leaves may only show chlorosis between the veins, or it may be spread throughout the leaf. This is different from nitrogen deficiency where yellowing occurs in the oldest leaves. If iron deficiency occurs, adding a chelated form of iron is best for uptake.
Million bells are also highly susceptible to Black Root Rot (Thielaviopsis) – I’ve seen this take out a good chunk of a crop. Symptoms include:
- Stunting of foliage and roots
- Plants in a tray will have uneven heights
- black areas on roots
- yellowing of leaves
Prevention is worth a pound of cure with this disease, as it is difficult to eradicate once established. Important steps to take include:
- Proper Sanitation. To avoid an issue with Black Root Rot year after year, immediately dispose of diseased plants, limit water splashing, and sanitize benches, floors and used pots/plug trays. Always physically wash surfaces with a cleaner to remove organic matter, then follow up with a disinfectant such as KleenGrow (ammonium chloride compound).
- Consider prophylactic applications of fungicides on plug trays. Products include Senator (thiophanate-methyl) or Medallion (fludioxonil). Preventative applications are an especially good idea if you’ve issues in the past. Adding bio-fungicides containing Trichoderma harzianum (e.g. Rootshield, Trianum) may also help.
- Lowering your pH. This disease is significantly inhibited by a lower pH – between 5.0 and 5.5.
- Manage fungus gnats and shoreflies, since these insects can spread Black Root Rot between plants. Treatments include nematodes, Hypoaspsis mites , or applications of Dimiln (diflubenzuron) or Citation (cyromazine).
If already established, rotated applications of Senator and Medallion may limit Black Root Rot, but are unlikely to cure it.
Lastly, Million Bells are highly attractive to aphids. With baskets hung up in the greenhouse, they can be “out of sight, out of mind”, but regular monitoring is needed to prevent large aphid outbreaks. Place sticky cards directly in baskets, and routinely check plant material for aphid cast skins and honeydew.
Once aphids are detected (and they will be!), applications of Beleaf (flonicamid), Enstar (kinoprene) or Endeavor (pymetrozine) will usually take care of them. However, be aware that all of these insecticides take around 4-5 days to start causing aphid death.