Plant Nutrition 101 #7
Non-Metal Micronutrients

by: Riley Holly

Up to now, we have looked at the metal micronutrients. As with the metals, the  non-metals
∑      boron (B),
∑      chlorine(Cl),
∑      molybdenum(Mo)
while necessary for successful plant growth, are usually abundant in the soil. However, if plant material is continually removed without replenishing, these nutrients will eventually become deficient. This problem is usually overcome by  composting, thus returning the nutrients to the soil

Molybdenum is required for the plantís use of nitrogen, and has a role in plant hormones.  It is slightly mobile in plants, but is bound in the soil, which reduces its probability of leaching. In low pH soils (acid), molybdenum is less available.  Some of the deficiency symptoms are:
††††††††††† -Stunting and lack of vigor
††††††††††† -Interveinal chlorosis of older leaves progressing to younger leaves, then necrosis ††††††††††††††††††††††††††††††††† of interveinal areas
††††††††††† -Marginal scorching, and mottling
††††††††††† -Cupping, rolling of older leaves
††††††††† -Yellow spotting of citrus
Boron regulates carbohydrate metabolism and differentiation of meristematic cells. It is not mobile in most plants and  tends to leach in the soil. Some of the deficiencies are:
††††††††††† -Death of terminal growth
††††††††† -Meristems
††††††††††† -Thickened, wilted, curled, chlorotic  leaves
††††††††††† -Soft or necrotic spots on fruits, tubers
††††††††††† -Reduced or improper pollination
††††††††††† -Dieback of roots and shoots
With an excesses of boron, one rarely observes any symptoms.  
Availability of boron is reduced in soils with a pH less than 5.5
Chlorine is required for photo-synthesis, helping prevent desiccation, and increasing disease resistance.  Chlorine is mobile in plants, and having a negative valance, does not bind with soil, therefore tending to leach out.
Some of the deficiency symptoms of chlorine, though rarely seen are:
††††††††††† -Wilting followed by chlorosis & necrotic spotting of

-Branching of lateral roots
††††††††††† -Leaf-bronzing

Excesses of chlorine may be seen as:
 †††††††††† -Poor growth, and Marginal leaf necrosis
of chlorine deficiency will show up first in the older leaves because of its mobility within the plant.
This completes the basics of the symptoms and needs of the plants in general for the 17 known plant nutrients.  Each plant will have a different reaction to the deficiency or excess of an individual nutrient.  Some nutrients are affected by the need for other nutrients.  Many mimic the symptoms of others in a particular species.  Hopefully this brief review will help you spot a problem before it is too late to correct.  Soil type and nutrient content, pH, and other factors need to be considered; it might be a pathogen or pest.
So keep watching for signs of stress in your plantings, and use the symptoms given to help you on the way to healthy plants