Stella Otto: The Backyard Fruit Gardener

Today's Tip: Mow vegetation short around the base of fruit trees and bushes to reduce winter habitat for rodents.

Preserving our Pollinators

We are all crit­i­cally depen­dent on pol­li­na­tors for our food, whether we grow our own or buy it at the mar­ket. Pol­li­na­tors are respon­si­ble for pro­duc­tion of nearly 75 per­cent of the plants we eat. That trans­lates to one in three bites of the food and drink we con­sume daily.

Take a moment to con­sider how rad­i­cally our diets would change if we were to become pri­mar­ily reliant on wind-pollinated crops such as wheat and corn. Many of our fruits and veg­eta­bles would dis­ap­pear from our din­ner plates. So would meat, as the ani­mals are reliant on pol­li­nated for­ages for much their diet too. We’d have no more fruit juice to drink. Would we become ever more reliant on corn syrup sweet­ened bev­er­ages? It’s not a food future most of us would like to envision.

Pol­li­na­tor Aware­ness Month

We depend on pollinators for 1 in every 3 bites of food we eat.

We depend on pol­li­na­tors for 1 in every 3 bites of food we eat.

June is Pol­li­na­tor Aware­ness Month, with National Pol­li­na­tor Week cel­e­brated dur­ing the third week of June (20th – 26th, 2016). It is a good time to reflect and remind our­selves of the part we play in pro­tect­ing or destroy­ing our pol­li­na­tor pop­u­la­tion. As fruit gar­den­ers in tem­per­ate North Amer­ica, we think of bees, mainly honey bees, as our pri­mary pol­li­na­tors. How­ever, there are many more pol­li­na­tors, about 200,000 species actu­ally. Approx­i­mately 1,000 of these species are ver­te­brates — birds, bats, and small mam­mals. In trop­i­cal cli­mates and other regions of the world, these other pol­li­na­tors can play a roll in fruit pro­duc­tion as well. The remain­ing 99.95 per­cent of the pol­li­na­tor pop­u­la­tion are ben­e­fi­cial insects — bees, wasps, bee­tles, flies, but­ter­flies, moths, and ants.


Bees as Pri­mary Pol­li­na­tors of Fruit Crops

Let’s focus on the pri­mary fruit pol­li­na­tors: bees. Although honey bees are the first to come to mind, var­i­ous stud­ies have observed that there are over 150 species of bees present in com­mer­cial orchards and berry plant­i­ngs at some time dur­ing the sea­son. About half this num­ber, 75 dif­fer­ent species, pol­li­nate either stone or pome fruits. In a given sea­son, a core group of about 30 bee species will be present dur­ing bloom and respon­si­ble for the major­ity of pol­li­na­tion that occurs in orchards and berry plantings.

Beyond the tra­di­tional honey bee hive that most of us think of, dif­fer­ent bee species have var­ied nest­ing habits. Many, about 80 per­cent of the world’s species, are ground-nesters. They are the pre­dom­i­nant species that pro­vide pol­li­na­tion in stone fruit (cherry, peach, plum) orchards. At least 4 species of Bum­ble Bees are com­mon pome fruit pol­li­na­tors, that avail them­selves of old rodent bur­rows for nesting.

Honey bees (left) are important pollinators of fruit, but Mason bee species (right) are also active native pollinator species

Honey bees (left) are impor­tant pol­li­na­tors of fruit, but Mason bees (right) are also active native pol­li­na­tor species

While ground-nesting bees are gen­er­ally less com­mon in pome fruit (apple and pear) orchards, other cav­ity nest­ing bees, often found along orchard edges, in old bram­ble canes, or pithy stems of mullein or elder­berry plants are major pol­li­na­tors. The Osmia species, or Mason bee, and the var­i­ous car­pen­ter bees are all in this group. They are more fre­quent pol­li­na­tors of pome fruit orchards, emerg­ing from their cav­i­ties too late for stone fruit pol­li­na­tion. Black­ber­ries, rasp­ber­ries, and pears that have too low a sugar nec­tar to be strong attrac­tants of honey bees all ben­e­fit from the work of the var­i­ous later-emerging Mason bees.


Why the Bee Decline?

Why has there been a major decline in honey bee pop­u­la­tions in the last decade? Some answers may be obvi­ous and per­haps part of nature’s nor­mal cycle of pop­u­la­tion peaks and val­leys. Colony col­lapse dis­or­der, Var­roa mite infes­ta­tions, and other hive dis­eases have cer­tainly been at the fore­front. Sequenc­ing of the honey bee genome has shown them to pos­sess a greatly reduced num­ber of genes that code for detox­i­fi­ca­tion enzymes, when com­pared to other insect genomes. It is these detox­i­fi­ca­tion enzymes that make insects more resilient and resis­tant to dis­eases, viruses or chem­i­cal substances.

Pos­si­ble cli­mate change and weather pat­terns likely also play a part. The recent unusu­ally harsh win­ters expe­ri­enced in the north­ern United States and drought in the west and south­west make bee sur­vival much more chal­leng­ing. When cer­tain plants that serve as nec­tar sources die as a result of these weather events, food source bio­di­ver­sity dimin­ishes. Water, of course, is crit­i­cal for sur­vival for all life.

Gen­eral loss of habi­tat over time has been another con­trib­u­tor. As a line from a Joni Mitchell song of the 1970s says, “We paved par­adise and put in a park­ing lot.” That leaves less habi­tat for ground dwelling pol­li­na­tors. The advent of the man­i­cured and highly main­tained sub­ur­ban lawn does likewise.

Honey bee hive boxes are often rented to pollinate commercial orchards

Honey bee hive boxes are often rented to pol­li­nate com­mer­cial orchards

Sev­eral “envi­ron­men­tal” groups, often using highly emo­tional rhetoric to spur their fundrais­ing, have put a tar­get on the back of our nation’s farm­ers and their use of crop pro­tec­tion pes­ti­cides with­out tak­ing a look in the mir­ror to con­sider their own part in the sit­u­a­tion. Cer­tainly, we have under­gone a major shift in pes­ti­cide use over the last cen­tury while try­ing to fig­ure out how to feed an ever expand­ing pop­u­la­tion. As these highly vocal groups have railed against broad spec­trum, envi­ron­men­tally per­sis­tent pes­ti­cides (and I am not say­ing those mate­ri­als were good), they may have dri­ven food pro­duc­ers and con­sumers to favor mate­ri­als that were just as dam­ag­ing or worse. Under the guise of safer, nat­ural, or “organic” they have encour­aged use of pes­ti­cides such as neem oil, pyrethroids, and spin­osad that are all toxic to bees and other ben­e­fi­cial insects. Even the sub­stances that bee­keep­ers them­selves applied for con­trol of Var­roa mite have been shown to have effects on repro­duc­tive capac­ity and longevity of honey bees.

What Gar­den­ers Can Do to Help

It is unlikely that we can quickly and mirac­u­lously solve the com­plex prob­lem of pol­li­na­tor decline on a global scale. How­ever, as indi­vid­u­als, we can take action toward solu­tions locally. As many small and dis­jointed pieces have cre­ated the prob­lem, the power of many small efforts may pro­vide the turn­around and solu­tion. Here are some steps you as a gar­dener can take:

Plant for pollinators

  • Diver­sity is impor­tant. The pollen and nec­tar of each plant species con­tribute dif­fer­ent nutri­ents to the pol­li­na­tors’ diets.
  • Pro­vide food sources that bloom through­out the sea­son. This could include flow­ers, shrubs, and trees.
  • Native or indige­nous plants are most likely to pro­vide the nour­ish­ment needed by the local pol­li­na­tors. Con­sult these sources for some appro­pri­ate plant selec­tions for your grow­ing region:

Cre­ate favor­able habitat

  • Pro­vide appro­pri­ate habi­tat. Mate­ri­als such as mud or waxy leaves are often used for nest building.
  • Build and place nest boxes for soli­tary bee species.  Find how-to instruc­tions here.
  • Clean, safe water is as crit­i­cal for pol­li­na­tor sur­vival as it is for our own. Fresh as well as muddy, min­eral rich water can be pro­vided in shal­low con­tain­ers or depres­sions so that pol­li­na­tors can drink with­out drowning.

Reduce your impact

  • Do your part to min­i­mize urban­iza­tion and increase green spaces.
  • Reduce your pes­ti­cide use by sub­sti­tut­ing more pol­li­na­tor favor­able cul­tural prac­tices when possible.
  • Know your pes­ti­cide. When you do choose to use one, select pollinator-safe choices.
  • Use pes­ti­cides only accord­ing to label direc­tions and apply when there will be no drift, typ­i­cally early in the morn­ing or near dark.

    Be aware of bees on blooming ground covers

    Be aware of bees on bloom­ing ground covers

  • Do not apply pes­ti­cides dur­ing fruit bloom. Be aware of any bloom­ing ground cover where pol­li­na­tors may be active and mow before appli­ca­tion if necessary.
  • Liq­uid for­mu­la­tions are gen­er­ally safer for bees. If pos­si­ble, avoid using pes­ti­cides that come in the form of dusts or wet­table pow­ders. Micro-encapsulated pes­ti­cides can be par­tic­u­larly dan­ger­ous as they are car­ried back to the hive like grains of pollen.

Edu­cate and encour­age oth­ers, espe­cially our children

  • If you would like to learn and under­stand more about bees, this pub­li­ca­tion, Bee Basics: An intro­duc­tion to native bees, offers con­sid­er­able information.
  • Horn faced bees are generally non-aggressive

    Horn faced bees are gen­er­ally non-aggressive

    Horn faced bee

    Horn faced bees are one of many native species and are impor­tant pol­li­na­tors of fruit