Deficiencies Got You Down?

This post was contributed to by Abigail Wiesner and Chevonne Dayboll.

As we move through production for fall and winter crops a refresher for nutrient deficiencies feels appropriate.

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

How to Spot a Nutrient Deficiency

Early detections of any problem can be caught with regular monitoring. Detection is STEP ONE:

Figure 1. Common nutrient deficiency indicators for floriculture crops.

Nutrient Mobility: When deficient, mobile nutrients will move to the new growth, but immobile nutrients will be trapped in the old growth. A quick scan of where the damage is occurring can help to narrow the potential culprits.

Stunted growth: If plants are looking shorter than normal, crop wide this can be a sign of nitrogen (N) or phosphorus (P) deficiency, especially if the older growth also looks yellowed. Individual or clustered groups of stunted plants are more likely to be caused by diseases.

Interveinal chlorosis: Dark green leaf veins with light green to yellowed leaf tissue? Sounds like a deficiency in magnesium (Mg), copper (Cu), iron (Fe) or manganese (Mn). Magnesium deficiency should show up in the bottom leaves first since it’s a mobile nutrient. Copper, iron, and manganese are immobile, so expect to see the chlorosis in the newest leaves initially. Of course, as the deficiency progresses, all leaves can show symptoms.

Leaf margins: If a border around the outer edge of a plant’s leaf looks yellow, purple, red, or brown it might be a potassium or calcium deficiency. This can also be a sign of pesticide or fungicide phytotoxicity, so review your spray records carefully.

This Ball Seed nutrient disorder diagnostic key could be a helpful resource for narrowing down your issue.

STEP TWO is to consider your inputs, irrigation and fertilizer. What and when was the last application? Is the application equipment properly calibrated and in working order (ie. Any clogs or drips)? Investigating these can help determine WHY a problem may have occurred.

STEP THREE is to conduct tests. Use an in-house pH / EC meter and compare results against your records and recommended ranges. For further confirmation, send samples for lab analysis.

Case Studies

Poinsettia

Common deficiencies are more likely to appear in mid-fall, but in order to head them off, it’s important to keep track of your E.C. and pH levels now.

For best results, maintain a feed E.C. between 1.0 and 2.5. Higher E.C. values will allow salts to accumulate, which will inhibit nutrient uptake. High E.C. can also cause young roots to burn – which provides an entry point for root rot problems. An optimal pH is in the range of 5.8-6.2. A pH greater than 6.5 will stunt growth, and iron deficiencies will eventually occur. Bi-weekly testing of these indicators and keeping good fertility and spray records can help you to understand what type of corrective action to take if a problem arises.

As with any nutritional problem, symptom location can help to narrow down the culprits.

Symptoms in the older, more mature leaves are typically caused by nitrogen (N), phosphorus (P), and/or magnesium (Mg) deficiencies.
- From late August to early September, phosphorus will be in high demand as the plants switch from vegetative growth to flower initiation. Consider adding supplemental P at this time, keep track of P levels in your growing media and watch for interveinal chlorosis on older leaves first. Read more about these demands here.
Symptoms in new or younger growth suggest micronutrient deficiencies such as calcium (Ca), iron (Fe), sulfur (S) or molybdenum (Mo).

Interested to learn more but don’t want to read another article? Watch this Tech On Demand video clip to hear about poinsettia deficiencies from the Ball Seed experts.

Rosemary

Are you seeing interveinal chlorosis of new leaves in your rosemary? While this is a clear symptom of iron deficiency, now you need to ask…how did that happen?

A recent article by Dr. Brian Whipker and Patrick Veazie from NC State University highlighted the importance of figuring out HOW a deficiency problem occurred. The iron deficient rosemary plants were found to be underneath a dripping irrigation nozzle. The extra moisture in the substrate prevented iron uptake by the plant. Additionally, a limestone additive altered soil pH above a suitable range, contributing to the deficiency. Find the full article here and another video specific to rosemary production here.

This case study perfectly demonstrates that knowledge of your irrigation patterns and growing media’s pH is essential to keep nutrients available to the plant. If you stray too far from the target range for your crop and media, nutrients will get converted to forms that are not available to the plant or prevent uptake, turning your fertilizer solution into very expensive waste!

Latest Nutrient Information

Check out this three-part video series produced by researchers at NC State University. Each video focuses on a different nutrient, reviewing fertility and use, deficiency diagnostics, and mimics, all specific to floriculture crops.

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