Symptoms The term chlorosis means a general yellowing of the leaves. Many factors contribute to chlorosis.

Size: px

Start display at page:

Download "Symptoms The term chlorosis means a general yellowing of the leaves. Many factors contribute to chlorosis."

Amos Bradley
6 years ago
Views:

CMG GardenNtes #223 Irn Chlrsis f Wdy Plants Outline: Symptms, page 1 Similar symptms, page 2 Causes and

page 3 Other cntributing factrs, page 4 Plant selectin right plant, right place, page 4 Irn additives, page 4

Sil applicatin f irn sucrate, page 6 Fliar applicatins, page 6 Trunk injectins, page 7 Symptms The term chlrsis

Irn chlrsis refers t a yellwing caused by an irn deficiency in the leaf tissues.

In severe cases, leaves may becme pale yellw r whitish, but veins retain a greenish cast.

1 CMG GardenNtes #223 Irn Chlrsis f Wdy Plants Outline: Symptms, page 1 Similar symptms, page 2 Causes and cmplicating factrs, page 2 Calcareus sils, page 3 Over-watering, page 3 Sil cmpactin, page 3 Trunk Girdling Rts, page 3 Other cntributing factrs, page 4 Plant selectin right plant, right place, page 4 Irn additives, page 4 Lwering sil ph, page 5 Sil applicatins f irn sulfate plus sulfur, page 5 Sil applicatins f irn chelates, page 6 Sil applicatin f irn sucrate, page 6 Fliar applicatins, page 6 Trunk injectins, page 7 Symptms The term chlrsis means a general yellwing f the leaves. Many factrs cntribute t chlrsis. Irn chlrsis refers t a yellwing caused by an irn deficiency in the leaf tissues. The primary symptms f irn deficiency include interveinal chlrsis, i.e., a general yellwing f leaves with veins remaining green. In severe cases, leaves may becme pale yellw r whitish, but veins retain a greenish cast. Angular shaped brwn spts may develp between veins and leaf margins may scrch (brwn alng the edge). [Figure 1] Figure 1. Symptms f irn chlrsis include yellwing f the leaf with veins remaining green

2 Irn is necessary fr the frmatin f chlrphyll, which is respnsible fr the green clr in plants and necessary fr phtsynthesis (sugar prductin in plants). Any reductin in chlrphyll during the grwing seasn reduces plant grwth, vigr, and tlerance t stress cnditins. Plants with reduced vigr frm irn chlrsis are mre prne t winter injury and winter injury may aggravate an irn chlrsis prblem. Weakened plants als are mre susceptible t ther diseases and insect infestatins Irn is nt very mbile within plants. Plants use their stres f irn in new leaves as they create them s irn chlrsis shws first and mre severely n the newer grwth at branch tips. Leaves may be smaller than nrmal. Leaves may eventually curl, dry up, and fall. Fruits may be small with a bitter flavr. Mildly affected plants becme unsightly and grw prly. In severe cases individual limbs r the entire plant may die. It is cmmn fr irn chlrsis t shw n a single branch r n ne side f a tree. This is particularly cmmn fr plant species with marginal winter hardiness fllwing winter injury. Plant species and varieties vary greatly in their susceptibility t irn deficiency. Chlrsis usually develps as an verall yellwing f needles n junipers, pines, and ther evergreens. Similar Symptms. Irn chlrsis symptms can be cnfused with ther prblems. In the high ph sils f Clrad, an irn chlrsis prblem may actually be a cmbinatin f irn and manganese deficiencies. It is cmmn fr chlrtic trees t shw a respnse t bth irn and manganese treatments. Zinc and manganese deficiencies result in similar leaf symptms. Irn chlrsis appears first n the yunger r terminal leaves. Under severe cnditins, it may prgress int lder and lwer leaves. By cmparisn, zinc and manganese deficiencies typically appear first n lder, interir leaves. Nitrgen deficiency shws as a unifrm yellwing f the entire leaf (including the veins). Nitrgen deficiency shws first in the lder leaves, while irn chlrsis shws first in the newer grwth. Damage frm sil sterilants (i.e., Pramitl, Atrazine, Simazine, Ureabr, and Diurn) used t prevent weeds result in similar symptms. With these weed killers, the leaf tissue alng the vein remains green. With irn chlrsis, just the vein itself remains green. Natural aging f tissues may create similar symptms in sme plants. Rt and trunk damage and sme virus, phytplasmas, and vascular wilt diseases may cause similar leaf symptms. Causes and Cmplicating Factrs The factrs leading t irn chlrsis are cmplex and nt fully understd. A number f chemical reactins gvern irn availability and cntribute t the cmplexity f irn chemistry in sils. Many envirnmental factrs als create r cntribute t irn deficiency. These factrs need t be evaluated and alleviated t the extent pssible. In many situatins, attentin t watering and sil cnditins will satisfactrily crrect minr irn chlrsis prblems

3 Calcareus Sils Many Clrad sils are naturally high in lime (calcium carbnate and ther calcium cmpunds) which raise the sil ph abve 7.5. In these calcareus sils, irn chlrsis is cmmn n susceptible plants. Clrad sils are abundant in irn, as evidenced by the cmmn red rck frmatins. In alkaline sils (ph abve 7.0), irn is rapidly fixed thrugh a chemical reactin int insluble, slid frms that cannt be absrbed by plant rts. Such irn will be tied up indefinitely unless sil ph changes. Sil applicatins f irn alne are ineffective, as the applied irn will quickly be cnverted t these unavailable slid frms. Over-Watering Irn chlrsis is a cmmn generic symptm f ver-watering. Overly wet r dry sils predispse plants t irn chlrsis. Irn chlrsis is mre prevalent fllwing wet springs, and where gardeners ver-water in the spring. In western calcareus sils, irn chlrsis can be mderated by eliminating springtime ver-watering. Dry sils can als lead t nutrient deficiencies as nutrients are absrbed in slutin with water. Severe cases f irn chlrsis invlving acid-lving lving plants may nt be crrected thrugh imprved irrigatin practices. It is cmmn fr gardeners t allw sprinkler cntrl settings t remain unchanged frm the high summer water needs t the lwer water needs f spring and fall. In this situatin, the yard receives as much as 40% mre water than is needed in the spring and fall. Such ver watering can cntribute t irn chlrsis.. Fr details, refer t CMG GardenNtes n irrigatin management. Sil Cmpactin Sil cmpactin and ther cnditins that limit sil air infiltratin (like surface crusting and use f plastic mulch) predispse plants t irn chlrsis by limiting effective rting area and sil xygen levels. Plants that have smaller rt systems have less chance f finding available irn. These are key cntributing factrs in clayey sils. Using rganic mulch (like wd r bark chips) helps prevent and reduce sil cmpactin. Avid the use f plastic under rck mulch arund landscape plants. Fr details n mulching and sil cmpactin, refer t CMG GardenNtes #215, Sil Cmpactin, and #245, Mulching with Wd/Bark Chips, Grass Clippings, and Rck. Trunk-Girdling Rts Irn chlrsis is a cmmn early symptm f trunk girdling rts in trees. The primary cause f trunk girdling rts is planting trees t deep. Trunk girdling rts can lead t decline and death sme 20 years after planting. In tree planting standards, the tp f the rt ball shuld rise slightly abve grade (i.e., 1-2 inches abve grade) fr newly planted trees. At least tw structural rts shuld be lcated in the tp 1-3 inches f the rt ball. Fr additinal infrmatin n tree planting, refer t CMG GardenNtes #633, The Science f Planting Trees. On established trees, the trunk-t-rt flare shuld be nticeable. If the trunk ges straight int the grund, suspect planting prblems and pssible develpment f trunk girdling rts ver time. T check, perfrm a rt cllar excavatin (carefully remving the sil arund the base f tree) and examine the trunk/rt flare

4 Other Cntributing Factrs Plant Selectin Right Plant, Right Place Plant cmpetitin In susceptible plants, cmpetitin frm adjacent lawns r flwers may aggravate irn chlrsis. Replace the grass under the tree canpy with wd/bark chip mulch. Winter injury Trees with cankers and ther winter injuries are prne t irn deficiency. (Winter bark injury n tree trunks is caused by winter drught.) Sil rganic matter Organic matter is a key t successfully gardening in Clrad s sils. Ideally, the sil s rganic cntent shuld be increased t 5%. Hwever, excessive amunts may aggravate irn prblems. Excessive salt levels High sil salt levels adversely affect uptake f water and nutrients, including irn. Fr details, refer t CMG GardenNtes #224, Saline Sils. Sil temperature and light intensity Extreme sil temperatures and high light intensity may increase irn chlrsis prblems. Use an rganic mulch t mderate sil temperature. Shading may help sme crps. Acid-lving plants Acid lving plants are highly susceptible t irn chlrsis and nt suited t Clrad s sil cnditins. These include blueberries, azaleas, rhddendrn, flwering dgwd, and heather. Nutrients Excessive levels (frm ver-applicatin) f phsphate, manganese, cpper, r zinc may aggravate irn chlrsis. In Clrad s high ph sils, the best methd t prevent irn chlrsis is t select plant species tlerant f high sil ph and less affected by lw irn availability. Avid planting the mre susceptible species (Table 1) n sils prne t irn chlrsis prblems (ph abve 7.5, cmpacted, clayey, r wet sils). Table 1. Examples f Plants with High Susceptibility t Irn Chlrsis Amur maple Dawn redwd Nrthern red ak Apple Duglas-fir Peach Arbrvitae Elm Pear Aspen Flwering dgwds Pin ak Azalea Grape Pine Beech Hneylcust Raspberry Birch Hrse chestnut Red maple Bxelder Juniper Rhddendrn Bumald spiraea Linden Silver maple Cherry Lndn plane tree (sycamre) Spruce Ctneaster Magnlia Crabapple Muntain-ash Irn Additives Unfrtunately, there is n easy, inexpensive, r lng-term crrectin fr irn chlrsis. Treatments may be rather expensive and give disappinting results.plant and sil cnditins vary greatly s there is n single apprach that is cnsistently best. Fcusing n reducing springtime ver-watering, sil cmpactin and ther cntributing factrs is can be effective in mitigating irn chlrsis in sme situatins

5 The first step in using irn additives is t knw the sil ph and free-lime (calcium carbnate) cntent. These sil factrs directly affect the success f any apprach. Determine sil ph by sil test. When the ph is abve 7.5, effective appraches are limited. T check fr free-lime, place a runded tablespn f dry crumbled sil in a small cup. Misten the sil with vinegar. (The sil needs t be thrughly mistened, but nt swimming in vinegar.) If the sil-vinegar mix fizzes r bubbles, it has free-lime. High lime cntent is typical f sils with a ph abve 7.5. A standard apprach in treating irn chlrsis is t lwer the sil s ph. Lwering the ph is impractical t impssible if the sil cntains free-lime. There are fur general appraches t irn treatments: 1) lwering the sil s ph, 2) sil irn treatments, 3) fliar sprays, and 4) tree injectins. Each has advantages and disadvantages. Each prcedure gives variable results depending n plant species and sil cnditins. The tw principal types f irn-cntaining prducts used fr irn applicatin include irn chelates and inrganic irn cmpunds (such as irn sulfate, ferrus sulfate). Several types f irn chelates are marketed under a variety f trade names. Sil ph dictates the type f chelate t use. Treatment f any irn prduct made mid-seasn may nt prduce satisfactry results. Lwering Sil ph with Sulfur Prducts A standard apprach used in many prducts is t lwer the sil ph. This apprach merits cnsideratin nly if the sil des NOT have free-lime (high calcium carbnate), and may shw effectiveness ver a perid f years. Due t the high ph and lime cntent f many Clrad sils, this apprach seldm merits cnsideratin. If irrigatin water is hard, the calcium carbnate (lime) in the water will cunter any acidifying effect. (As a side nte, it has been bserved that in sme lder gardens the ph has drpped belw natural levels as the lime cntent is slwly leached ut with decades f irrigatin.) The ph is lwered by sil applicatins f sulfur prducts. See the prduct labels fr specific applicatin rate. (Use f aluminum sulfate t lwer sil ph is nt recmmended due t a ptential fr aluminum txicity.) Fr details n lwering ph, refer t the CMG GardenNtes #222, Sil ph. Sil Applicatins f Irn Sulfate Plus Sulfur A simple apprach is t apply a mixture f equal amunts f irn (ferrus) sulfate and sulfur t the sil. Examples f prducts include Cpperas, Jirdn Super Irn Green, HiYield Sil Acidifier Plus Micrs, and Fertilme Sil Acidifier Plus Irn. Over a perid f mnths t years, an imprvement may be nticed. When it is effective, treatments may last up t three r fur years, depending n sil cnditins. This apprach merits cnsideratin nly n sils withut free-lime. Fr trees, apply the mixture in hles arund the drip-line f the tree, as described fr chelates (see belw). Over time, the sulfur reacts t lwer sil ph in a lcalized area. Bradcast applicatins, that dilute the material ver a larger area, are less likely t give satisfactry results. Treat rws f berries r small shrubs by placing the mix in a furrw fur inches deep and inches away frm the plant. See specific label directins fr applicatin rates. Fr best results, treat the sil in spring

Sil Applicatins f Irn Chelates Sil applicatin f irn chelates may give a rapid respnse if the crrect chelate is used and ther cntributing factrs are minimal.

6 Sil Applicatins f Irn Chelates Sil applicatin f irn chelates may give a rapid respnse if the crrect chelate is used and ther cntributing factrs are minimal. Applicatins after May 1 st are less likely t shw results. Treatments may last less than a seasn t a cuple f years. Treat trees by placing the irn prduct in rings f hles in the grund beneath the dripline (uter reaches f the branches). Make hles 1½ t 2 inches in diameter, 6 inches deep and 12 inches apart in rings 2 feet apart. Fr smaller trees, make 2 t 3 rings f hles. Fr large trees, create fur t five r mre rings f hles, and rings may need t extend beynd the drip line. N hles shuld be made within 2½ t 4 feet f the tree trunk n established trees. [Figure 2] Drill hles in the sil with a pwer r hand auger, bulb planter, r small trwel, remving the sil cre. Using a punch bar that makes hles by cmpacting the surrunding sil may be less effective. T avid damage t shallw utility lines, have the area utility-staked befre starting. [Figure 2] Figure 2. Place sil additive in a ring f hles arund the drip line f the tree. In sils with a ph abve 7.5, nly special chelates frmulated fr a high ph are effective. Examples include EDDHMA (Miller s Ferriplus) r EDDHA (Fe Sequestrene 138). Due t its higher cst, these prducts have limited availability. See prduct label fr specific applicatin rates. In acid t slightly alkaline sils, try ther chelates like EDTA (Fe Sequestrene 330, Fertilme Liquid Irn) and DTPA (Miller s Irn Chelate DP). They lse effectiveness quickly as the ph rises abve 7.2 t 7.5. See prduct label fr specific applicatin rates. Sil Applicatins f Irn Sucrate Irn sucrate, a relatively new irn surce, is manufactured frm irn xide and mlasses t frm an irn-cntaining rganic cmplex with limited water slubility. It is less prne t staining due t its very lw slubility. Irn sucrate merits cnsideratin in high ph sils, and additinal scientific evaluatin is warranted fr Clrad sils. It is marketed as Lilly Miller Irn Safe. Fliar Sprays Fliar sprays f irn sulfate r irn chelates may prvide quick respnse, ften in a matter f days. Hwever, the treatment is ften sptty and nly temprary. Multiple applicatins per seasn may be needed. Effects will nt carry ver int subsequent years. Bth types f prducts are equally effective, but irn chelates are mre expensive. See prduct labels fr specific applicatin rates and instructins. With fliar applicatins, spray in the evening r n cludy days when drying time is slwer. A few drps f liquid dishwashing sap r cmmercial wetting agent will enhance sticking prperties

7 Fliar applicatins are generally nt recmmended due t applicatin limitatins. Cmplete cverage f all leaves is essential. Individual leaves nt treated may remain chlrtic. Cverage n large trees is impractical t impssible. There is a small margin between an irn cncentratin that will green up the leaves and a cncentratin that will cause leaf burn. Leaf tissues are rather prne t turn black frm an irn burn. Fllwing an irn sulfate fliar treatment, it is cmmn t see leaves that remain chlrtic, leaves that green up, and leaves with black burn spts n the same plant. Spray hitting the sidewalk, huse, and ther bjects may leave a permanent rusty disclratin. Chelated irn sprays are inactivated by sunlight. Trunk Injectins Prfessinal arbrists have trunk implant r injectin methds available fr treating irn chlrsis n large trees. Trunk injectins may last frm ne t five years. Refer t prduct infrmatin fr applicatin details. Injectins may create pathways fr decay rganisms t enter a tree. Additinal Infrmatin CMG GardenNtes n Sils, Fertilizers and Sil Amendments: #211 Intrductin t Sils #232 Understanding Fertilizers #212 The Living Sil #233 Calculating Fertilizer Rates #213 Managing Sil Tilth #234 Organic Fertilizers #214 Estimating Sil Texture #241 Sil Amendments #215 Sil Cmpactin #242 Using Manure #218 Earthwrms # 243 Using Cmpst #219 Sil Drainage #244 Cver Crps and Green Manure Crps #221 Sil Test #245 Mulching with Wd/Bark Chips, Grass #222 Sil ph Clippings and Rck #223 Irn Chlrsis #246 Making Cmpst #224 Saline Sils #251 Asking Effective Questins Abut Sils #231 Plant Nutritin Authrs: David Whiting (CSU Extensin, retired), Adrian Card (CSU Extensin), Carl Wilsn (CSU Extensin, retired), and Jean Reeder, Ph.D., (USDA-ARS, retired). Artwrk by David Whiting; used by permissin. Clrad Master Gardener GardenNtes are available nline at Clrad Master Gardener training is made pssible, in part, by a grant frm the Clrad Garden Shw, Inc. Clrad State University, U.S. Department f Agriculture and Clrad cunties cperating. Extensin prgrams are available t all withut discriminatin. N endrsement f prducts mentined is intended nr is criticism implied f prducts nt mentined. Cpyright Clrad State University Extensin. All Rights Reserved. CMG GardenNtes may be reprduced, withut change r additins, fr nnprfit educatinal use. Revised Octber

Symptoms The term chlorosis means a general yellowing of the leaves. Many factors contribute to chlorosis.

Symptoms The term chlorosis means a general yellowing of the leaves. Many factors contribute to chlorosis. Clrad Master Gardener sm Prgram Clrad Gardener Certificate Training Clrad State University Extensin GardenNtes #223 Irn Chlrsis Outline: Symptms, page 1 Causes and cmplicating factrs, page 2 Calcareus