Ample rain with cooler temperatures earlier this year boosted the blackberry production in the front yard vines which I had pruned back vigorously last fall due to overgrowth. The jungly, barbed tendrils are blossoming and fruiting to beat the band.
Close inspection of either a blackberry or a raspberry shows why these are called aggregate fruits. Unlike a strawberry, a blackberry fruit is made up of 75 to 85 tiny druplets.
Think of a fruit’s druplet as comparable to a single kernel on an ear of corn. Biologically, they are related.
No druplet can form unless its pistil is fertilized. Of the 100-125 pistils on a typical blackberry flower, 75-85 of them must be fertilized to yield a large, well-shaped berry.
Now that the summer heat has set in, the beautiful dark purple berries in my front yard are spotted with unpleasant-looking tan to milk chocolate druplets – a fact which I discovered when I went out this morning to harvest the ripe fruits.
I was hoping that the berry patch wasn’t suffering from an infestation of insects, mold or disease. These are all biotic disorders that home farmers must deal with fairly quickly to prevent what may amount to total devastation. Off to the internet I went to search for answers.
The good news – such as it is – is that the berries in my yard are perfectly safe to eat – although you won’t see many shipped to grocery stores. My aggregate drupal fruits are, alas, victims of two abiotic conditions: high temperatures and low humidity.
Specifically, these poor berries are suffering from heat stroke! Called white drupe or white druplet, the sudden recent hot, dry spell around here has taken moisture out of the air (which makes it feel more bearable outdoors) which allows more solar radiation through to the berries, turning groups of the druplets white and then brown.
Rigging up a shade may ease white drupe, a problem seen more in the early part of the fruiting season than later on. (We’ll see and I’ll be the judge of that.)
Sunscald is an abiotic blackberry disorder which is similar to white druplet and often occurs at the same time and on the same berries. It occurs when daytime temperatures rise above 90F. Direct exposure to the sun’s ray can raise this heat setting even higher and literally <https://www.merriam-webster.com/dictionary/blanch> blanch</a> or cook the fruit, right on the vine. The shaded side of the berry is usually just fine.
Shading the berries with their own leaves and re-orienting trellises away from direct sunlight can help reduce both forms of fruit blight.
Another tip is to pick berries every two to four days, depending on how fast they ripen.
Finally, some people use overhead irrigation to reduce fruit loss to sunscald and white drupe. This technique goes well beyond merely misting the plants. Instead, a lot of water is applied to completely wet the canopy and lower temperatures for as long as possible. If you try this method, be sure to water early enough before nightfall so that the fruit can dry.
What about blackberries that grow shriveled and small?
Berries that don’t develop many druplets may not be properly pollinated by neighborhood bees and wasps. Cool, wet weather during the flowering season can reduce bee and wasp activity.
This, in turn, reduces the amount of pollen (produced in the stamens of the flower) that the pollinators must move into contact with a pistil in order to fertilize an ovule which bears a single druplet.
Viruses can also cause underperforming druplets.
Nature protects the delicious fruits behind a thorny fence of intertwining canes which sport nettly leaves. Here are some insider tips on how to harvest blackberries without (much) pain.
- Harvest blackberries and raspberries before 10 AM or so, when the outside temperature is still relatively cool.
- Remember to take a container big enough to hold your harvest. It’s annoying to have to double back for this crucial item.
- Wear a hat – to prevent your own heat stroke.
- Wear rubber boots – and prepare to sweat in the heat. Berry barbs have a hard time sticking to thick rubber. Grab a pair of Wellies before you sally forth into the berry thicket.
- Don a plastic raincoat – the hardy kind little kids wear. Smooth, thick plastic is also an effective barrier against blackberry thorns and barbs. Again, be prepared to perspire.
- Take a rake – the iron-headed garden type with wide-spaced teeth is preferred over a punier leaf rake but even a long-handled broom can pin back the longest vines to make a path into the central areas.
- Wear one thick leather glove – and leave your other hand bare to pick the luscious fruits. The protected hand can pull back vines that are in the way.
- Bend down and lift vines – to reveal ripe berries hiding in the shade. Blackberries in a thicket are elusive. Look for them from different angles.
- Rinse the blackberries and let them dry – being on the alert for carpenter ants which hang around the berry patch and will crawl into your abode from the picked fruits.
- Blackberries are best consumed right away, even off the vine with no rinsing. Store uneaten fruits in a container with a tight-fitting lid in the fridge or on a paper-lined tray or plate for snacking.
- Share the bounty – if you find you are producing more fruit than you can possibly eat and don’t want to bake and freeze pies or put up jams to preserve them. Reward your friends and make new ones with the gift of blackberries and raspberries. Mmmmm.
