With the holiday season almost upon us, it’s time to turn our attention to Spring bedding crops. Although here for a brief window, the diversity of these crops means you’re bound to encounter some sort of disease and insect problems.
One way you can head off issues is to plan and prepare now. This post from January 2020 has important tips on sanitation for common spring crop diseases, dipsandearly sprays to prevent key pests, as well as tips on where to spend your biocontrol dollars.
With the holiday season over, it’s time to turn our attention to Spring bedding crops. Although here for a brief window, the diversity of these crops means you’re bound to encounter some sort of disease and insect problems.
One way you can head off issues is to plan and prepare now. This post has important tips on sanitation for common spring crop diseases, dipsandearly sprays to prevent key pests, as well as tips on where to spend your biocontrol dollars.
Investigating biocontrol options for our industry is always important, given the lack of registered insecticides in this country. Currently, we are relying heavily on two closely related chemicals – Beleaf (flonicamid) and Endeavor (pymetrozine) – for control of the foxglove aphid (Aulacorthum solani). If our battle with thrips (and Bemisia whitefly) have taught us anything, it’s to be prepared for chemical failure.
Unfortunately, biological control of foxglove aphid has been challenging so far. For example, my own research showed that Aphidoletes, a “generalist” aphid predator, actuallyhas lower preference for foxglove aphid than other species, and is less effective for this pest. However, a long-term project by Dr. Michelangelo La-Spina (Vineland Research and Innovation Centre) has found some results that get us closerto being able to control foxglove aphid WITHOUT resorting to pesticide sprays.
You know the old rhyme: “April showers bring May flowers, but what do May flowers bring? Aphids“. Or sometimes it seems that way, anyways, with Spring bedding crops.
To help guide your pest management program this year, our friends (superiors?) over at Michigan State Extension have released a handy list of which crops are likely to attract which pests. Keep reading for more info.
Aphis gossypii come in a variety of colors, as shown above. But all colors share one thing in common – black cornicles at the tip of their bodies. These can be seen with a hand lens.
Usually on this blog we bring YOU the information. Today it’s the opposite. I’m looking for a grower who has live melon aphid (Aphis gossypii) in their operation, and wouldn’t mind a researcher coming by to remove some of them to start a research colony with.
If you have some you wouldn’t mind parting with, please contact Rose Buitenhuis at 905.562.0320 Ext. 749 or firstname.lastname@example.org who can get in touch with our contact at Laval University. They might even name the colony after you…
As a refresher, Melon aphids tend to be the smallest aphid found in your greenhouse. They can come in a variety of color morphs – from pale green-yellow to dusky grey – but they ALWAYS have black cornicles (or “tail pipes”) at the end of their abdomen. They are common in crops like kolanchoe and gerbera and a variety of other spring crops.
If you comment on this blog post regarding aphids in your greenhouse only I (sarah) will see it.
Foxglove aphid feeding on pansy. Note the two dark-green spots on the abdomen and the dark leg joints which are characteristic of this pest.
Now that temperatures have cooled down, it’s time to start watching for foxglove aphid as your primary aphid pest, rather than green peach or melon aphid. Here’s links to 2 articles that were published this week that talk about this pest’s biology and control measures.
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.
Iron deficiency in Calibrachoa. The resulting yellowing can look similar to symptoms caused by black root rot or nitrogen deficiency.
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.
Yellowed plant growth (yellow circle) and dead plugs (orange circle) on a plug tray of Callibrachoa from black root rot.
Million bells are also highly susceptible toBlack 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 onplug 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 diseaseis 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.
Aphids tend to be found on flowers and new growth of Calibrachoa.
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.