Spray trees now to get rid of pesky in­fec­tions and pests

The Sacramento Bee - - Home & Garden - BY MARLENE SI­MON Spe­cial to The Bee

This is the per­fect time of year to be think­ing about spray­ing trees dur­ing their dor­mant sea­son. I’ll give two ex­am­ples of con­di­tions which war­rant spray­ing: fun­gal in­fec­tion and pest in­fes­ta­tion.

First, let’s look at a com­mon fun­gal in­fec­tion. A ques­tion I get asked in spring is “why are my peach or nec­tarine leaves curl­ing?” Leaf curl is caused by the fun­gus Taph­rina de­for­mans. The spores, spread by air or rain, thrive in wet con­di­tions. When they ger­mi­nate in spring, they in­fect the plant’s leaf tis­sue, caus­ing leaves to turn red, curl and pucker.

If the in­fec­tion is se­vere enough, the tree will de­fo­li­ate and fruit pro­duc­tion will be de­creased. If the leaves fall off, a new set will im­me­di­ately grow back with no symp­toms. How­ever, the spores will lay dor­mant on the tree sur­face dur­ing the dry heat of sum­mer. The fol­low­ing spring the spores will ger­mi­nate, caus­ing the symp­toms to re-emerge. If peach leaf curl is not con­trolled and al­lowed to man­i­fest year af­ter year, it can lead to an un­healthy, un­pro­duc­tive tree.

The dor­mant sea­son is the time to pre­vent this fun­gal in­fec­tion from at­tack­ing your trees, or treat ones with a prior out­break. Un­for­tu­nately, I have to tell peo­ple there is no im­me­di­ate ac­tion to take by the time symp­toms of peach leaf curl man­i­fest on peaches/ nec­tarines in spring.

The good news is that de­pend­ing on the sever­ity, cur­rent year fruit pro­duc­tion may not be im­pacted. How­ever, even if cur­rent year pro­duc­tion is am­ple, it is crit­i­cal to treat the af­fected tree the fol­low­ing win­ter. So how to treat this prob­lem? Liq­uid cop­per sprayed on the trees can pre­vent or min­i­mize this in­fec­tion. Here’s how:

Liq­uid cop­per is a generic term for CME (Cop­per Metal­lic Equiv­a­lent). The brands sold at nurs­eries are a cop­per am­mo­nium com­plex with 8% CME.

Best prac­tice is three sprays done be­fore the buds break in mid to late Fe­bru­ary, par­tic­u­larly if it’s a wet win­ter.

Thanks­giv­ing, Christ­mas and Valen­tine’s Day are good tar­get dates to spray.

Spray on a dry day with at least one dry day fol­low­ing.

Ap­ply us­ing a hoseend-sprayer — I like the Ortho Dial N Spray (sold at most nurs­eries). No mea­sur­ing is needed. Sim­ply pour the cop­per into the con­tainer, at­tach the hose and set the sprayer dial to rec­om­mended rate on the cop­per la­bel and spray.

Spray the cop­per onto the tree un­til all limbs are coated and it is drip­ping off the tree.

Any un­used cop­per can be poured back into orig­i­nal con­tainer.

Spray­ing a petroleum­based hor­ti­cul­tural oil onto the tree di­rectly af­ter cop­per ap­pli­ca­tion will help the cop­per “stick” to the tree. This oil is com­monly found at nurs­eries, and is ap­plied us­ing the same hose-end sprayer.

Although the ex­am­ple above is about peach leaf curl, liq­uid cop­per can also be used to con­trol other fun­gal in­fec­tions on fruit trees, roses, grapes and or­na­men­tals. These in­clude brown rot on apri­cots, pow­dery mildew on roses and grapes and var­i­ous leaf spots on many or­na­men­tal plants.

Next, let’s look at a few ex­am­ples of pest in­fes­ta­tion that can be treated by win­ter/spring spray­ing. Mealy­bugs, aphids, scale, white­flies and thrips are phloem suck­ing in­sects that can be con­trolled us­ing oils. These in­sects pierce into the plant’s sugar trans­port sys­tem (phloem) and suck out the tree’s car­bo­hy­drates. When their num­bers are high, their sug­ary ex­cre­ment can coat a plant or tree and drip down onto sur­faces be­low (of­ten mis­taken for the plant drip­ping sap). Most of these in­sects ei­ther over­win­ter as adults, eggs or lar­vae on a plant.

The dor­mant sea­son is the ideal time to spray a hor­ti­cul­tural oil to con­trol these var­i­ous pests. Dur­ing win­ter/spring these sprays can be ap­plied to ev­er­green and dor­mant plants, but avoid ap­ply­ing when a frost or rain is ex­pected. It is cru­cial to read the prod­uct la­bel care­fully to see if any side ef­fects may oc­cur on spe­cific plants.

Ap­pli­ca­tion/tim­ing — ad­here to the same guide­lines as stated above for liq­uid cop­per.

For win­ter/spring spray­ing, I pre­fer a petroleum-based hor­ti­cul­tural oil.

Some oils will be la­beled and mar­keted as “dor­mant” or “all-sea­son.” Re­gard­less, due to our high tem­per­a­tures start­ing early in the year, it is ideal to limit spray­ing plants to the win­ter sea­son to pre­vent oil-in­duced burn­ing.

I set an up­per tem­per­a­ture limit of 85 de­grees Fahren­heit for spray­ing of any oil.

The hor­ti­cul­tural oil will smother the pests, killing them.

The oil is short-act­ing ,so there is less chance of ben­e­fi­cial in­sects (such as la­dy­bugs and lacewings) com­ing in con­tact with it.

ASK THE PLANT LADY

Q: My Fi­cus lost its leaves when I moved it [from one lo­ca­tion in­side my house to an­other]. Is it dead?

A: The com­mon house­plant Fi­cus ben­jam­ina is very finicky when moved. Even with slightly dif­fer­ent light ex­po­sure and/or tem­per­a­ture, it will drop its leaves and put on a new set more suited to its cur­rent en­vi­ron­ment. This can take up­wards of a few weeks, so avoid mov­ing it dur­ing this pe­riod. Re­duce wa­ter­ing un­til new leaves emerge — the Fi­cus has re­duced hy­dra­tion needs with­out leaves. If you are con­cerned if the plant has died, lightly scrape the bark. If green un­der­neath, then it is still alive and just needs more time to ac­cli­mate and put new leaves on. Fi­cus re­quire mod­er­ate to bright light in­side and pre­fer to be slightly pot­bound, mean­ing you only trans­plant to a larger pot if the roots are lit­er­ally burst­ing out of the orig­i­nal.

CRAIG KOHLRUSS ck­[email protected]­nobee.com

The Plant Lady says it’s time think about spray­ing trees dur­ing their dor­mant sea­son.

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