This young leaf of a Mn-deficient Archontophoenix alexandrae shows the distribution of symptoms that separate Mn deficiency from late stage K deficiency. With Mn deficiency, symptoms are most severe towards the leaf base, whereas the reverse is true with K deficiency. Also note the longitudinal necrotic streaking in this Mn-deficient leaf. A K-deficient leaf would have marginal leaflet necrosis instead.

Boron Deficiency Stunted, necrotic-tipped leave Multiple or incompletely opened spear leaves Horizontal growth Abortion of flowers and fruits Death of the meristem Affects youngest leaves, etc.

Boron (B) Deficiency Extremely transient due to rainfall patterns Newest leaves show B status four or more months ago Leaf nutrient analysis may not be useful for determination of current B status

Abnormal opening of spear leaf. One of the most common symptoms of boron deficiency is abnormal opening of spear leaves. In this case, multiple spear leaves failed to open, suggesting that this is a chronic state of B deficiency that has been going on for many months. Often only a single spear leaf will not open normally, with either the basal portion partially open, or the tip partially open while the rest of the leaf remains tightly fused. A single leaf not opening normally may be indicative of the beginning of a chronic B deficiency state, or it may be just a transient B deficiency.

An open tip indicates that the deficiency became worse as the leaf opened. A single abnormally opened spear can be indicative of B deficiency. In this case, the base of the leaf is fused tightly, but the tip has attempted to open. This suggests that the deficiency became worse as this leaf developed, whereas a tight tip and more open leaf base indicates that the deficiency was more severe when the leaf first began its development.

Puckering leaflet is a symptom of B deficiency.

Corrugations also a symptom of B deficiency. Corrugations of new leaves is another common symptom of B deficiency. Corrugations also a symptom of B deficiency.

“Accordion leaf” If not corrected soon, this will result in death of the palm. In severe B deficiency, new leaves are very tightly compacted and crumpled in appearance. This is often called “accordion-leaf”. This is an acute phase of B deficiency, which can be transient, or if sustained, may become fatal to the palm.

“Hook leaf” is an early symptom of mild B deficiency. One of the earliest symptoms of mild, often transient B deficiency is “hookleaf”. These leaflet tips are so tightly bent, that if one attempts to straighten them out, they will tear instead. Often these hooked leaflet tips will fall off, leaving shortened leaflet tips. This symptom can occur anywhere along the leaf from the base to the tip of the leaf. “Hook leaf” is an early symptom of mild B deficiency.

Normal Queen Palm Chronic B deficiency This silhouette photo shows the sparse narrow leaflets produced by chronically B-deficient queen palms (on right) compared to a more normal leaflet width on the left palm. However, the tips of the leaves of the left palm also show the narrow leaflets characteristic of this deficiency.

Leaf tips have narrow, short leaflets. Leaflets may fall off. In queen palm, the tips of leaves often have very narrow, short leaflets. These terminal leaflets may drop off by themselves leaving the tip of the rachis bare as seen here.

These bare rachis tips are present on leaves of all ages here except for the youngest leaf. This is because the palm had been suffering from chronic B deficiency for a couple of years, but recently has begun to recover from it. Thus, although the bare rachis tip symptom was produced while the leaf was emerging, as these leaves mature and move down within the canopy, the symptoms move with them. To the uninitiated it would appear that the symptoms are occurring first on the oldest leaves, when in fact they were produced on young leaves, but the palm has since grown out of the problem. B deficiency symptoms appear in young leaves and remain throughout the life of the leaf. New leaf is okay, so B has been corrected.

New leaves are reduced in size and the leaf tips appear to be cut off. On fan palms, new leaves of B-deficient palms are reduced in size and may have the leaflet tips cut off as with feather palms. Hookleaf symptoms have also been observed in fan palms.

Over production of auxin results in leaf bending. One leaf bent = severe leaching of B due to a very heavy rainfall 4 or 5 months ago Entire crown bent = chronic B deficiency Boron deficiency can cause excessive auxin production and therefore sharp bending of individual leaves (seen here), or the entire crown. Bending of a single leaf suggests a severe leaching of B due to a very heavy rainfall when this leaf was developing 4 or 5 months ago. Subsequent leaves may emerge normally. However, if the entire crown begins to bend, this suggests a chronic B deficiency that has been going on for many months or even years.

How many B deficiency symptoms can you find? Boron deficiency often causes palm stems to bend sharply in response to excess auxin production. This palm is also showing other B deficiency symptoms such as “little leaf” and the tightly packed leaflets and truncated leaf tip.

This Royal Palm is in need of triage! This royal palm is suffering from severe B deficiency, with tiny new leaves being produced and both a sharp turn in the growing axis and twisting of the leaves (epinasty) due to hyperauxiny .

Flower necrosis on Queen Palm Flower necrosis is a common symptom of B deficiency in palms. This is also indicative of lethal yellowing disease, except that this is an inflorescence of a queen palm, a species that is not susceptible to LY.

Premature fruit drop is a common symptom of B deficiency Premature fruit drop is a common symptom of B deficiency. In the case of coconuts, this is also a symptom of lethal yellowing disease. In that disease, however, the stem end of the nut will have a blackened water-soaked appearance, whereas B-deficient coconuts will brown naturally on any side as seen here. Premature fruit drop

Compare with lethal yellowing on coconut – water soaked spots on fruit. One of the first symptoms in coconuts (and other palm species) is the blackening of the flowers or the premature falling of the fruits (nuts). Note the blackening of the nut at the end that was attached to the inflorescence stalk.

Nitrogen (N) Quite uncommon Except Veitchia sp. Uniform yellowing or discoloration of the foliage Reduced growth rate Affects older leaves or entire plant Nitrogen deficiency is quite uncommon on most species of palms in the landscape, but in Ptychosperma and Veitchia spp. N is usually the most important limiting element. In most other species, the most limiting element is potassium. Note here that the older leaves are uniformly yellow or yellow-green, while the youngest leaf is green. This is because N, like all macronutrients, is mobile within the plant. Under deficiency conditions, the plant is able to resorb N from the older leaves and retranslocate it up to the youngest expanding leaf, thus allowing for continued growth in the absence of sufficient N in the soil.