Every year it seems that a few of the same culprits impact our harvest quality. Insanity can be defined as: doing the same thing over and over again and expecting different results. Have you put a plan in place to minimize the causes (hail accepted) that impacted your harvest last year?
Here’s a few of the “regulars” that cause us grief:
Earwigs feed most actively at night and seek out dark, cool, moist places to hide during the day. Common hiding places are under loose clods of soil, boards, or dense growth of vines or weeds or even within fruit damaged by other pests such as birds or cutworms. Crack open any split pit and out they come!
Female earwigs dig cells in the ground in the fall and winter where they lay masses of 30 or more eggs. Eggs hatch into small, light brown nymphs and remain in the cell protected and fed by their mother until their first molt. Second-instar nymphs may forage at night but still return to the nest during the day. Third- and fourth-instar nymphs are darker and forage on their own. Usually there is one generation a year, but females produce two broods. Part of the earwig population hibernates during the winter as pairs buried in cells in the soil.
European earwigs feed on a variety of dead and living organisms, including insects, mites, and growing shoots of plants. They are voracious feeders on soft-bodied insects such as aphids and insect eggs and can exert significant biological control under some circumstances. Therein lies the catch 22. Early in the season earwigs are a beneficial. At some point mid-summer they transform from Dr. Jekyl to Mr. Hyde when they start feeding on ripening fruit.
Heads Up! I’m seeing LOTS of earwigs and getting lots of reports about their numbers. Here’s how to get an idea of the population numbers in your orchard. Find several small pieces of plywood or carpet and lay them out on the orchard floor. Give it several days and look underneath, then give us a call to discuss your management plan!
Stink bugs are generally native to our region and are notable examples of locally migratory insects that live on a broad complex of plant hosts. Principal hosts found along the orchard edge or resident within herbicide strips include mullein, mustard, dock, plantain, milkweed, mallow, morning glory, thistles, and vetch.
Adults usually migrate into the orchard once other host plants dry out. Irrigated tree fruit become very attractive to the stink bug complex during drought conditions, leading to late season feeding damage in pear, apple and peach orchards. Stinkbugs have a proboscis (mouth part) that acts like a hypodermic needle. They pierce the fruit skin and draw out the cellular contents of the fruit flesh, leaving behind dry cell walls that appear as corking when peeled.
As you might suspect, stink bugs derive their name from the production of pungent and offensive chemicals released when they are disturbed. Relatively mild winters and softer (more species specific) insecticide programs help in fostering their overwintering success.
It’s important to note that stink bug feeding differs dramatically among stone fruit, apple and pear. Catfacing injury to peaches by stink bug is very similar to that of lygus, another type of plant bug. On apple, fruit damage appears as shallow, circular, light brown to white spongy pockets in the fruit flesh, usually from 3/16” – 3/8” in circumference, and 3/16”– 5/15” in depth. Stink bug feeding can easily be mistaken for bitter pit. Typical feeding injury tends to be on the stem end or sides of the fruit, as those parts of the fruit surface are easier for the insect to stand on, and most likely to be covered by foliage, which provides protection as the bug feeds. On apple, stink bug feeding and cork spot are distinguishable by several differences in the depressions on the apple surface. With stink bug feeding, the edge of the depression on the fruit surface is gradual instead of abrupt, as observed with cork spot. The corky flesh is always immediately beneath the skin in stink bug injury, and often separates from the skin. Stink bug injury always has a small puncture near the center of the feeding depression. You’ll need to have a magnifying glass!
Stink bugs are very difficult to manage for a number of reasons. They have a broad host range, including many crops and broadleaf weeds. They are highly mobile, frequently moving between weed hosts and fruit trees. They tend to be more active in the evening and during the night. Insecticide applications made during the day may not come in direct contact with the insect, which reduces the effectiveness of the materials. The classes of insecticides that have good activity on stink bugs are pyrethroids and neonicotinoids.
Stink bugs are fast and good at hiding. They will move to the backside of a limb or fruit as you approach. Take an early morning walk when it’s cool and they aren’t moving as fast. Look inside the dense parts of the tree. If you have a lot of alfalfa and/or other legumes as part of your cover crop, take a close look there. Use a sweep net (http://www.forestry-suppliers.com/product_pages/Products.asp?mi=52801&itemnum=53698&redir=Y ) if you have one. Plant bugs like legumes! Don’t let your cover crop dry out!!!
Greater peach tree borer aka crown borer is easy to overlook since it doesn’t show up at harvest by damaging fruit. Instead it shows up slowly during the summer as weak and stressed or dying trees. Make sure it’s part of the “list” of things you look for as you walk the orchard. Inspect for damage at the soil line.
Pheromone mating disruption is the most common and effective means of controlling this pest in our area. Mating disruption does have limitations and you need to know them. Give Dan or me a call and we can discuss the pros and cons. If trunk drenches are your choice of control use a material with maximum residual and efficacy. Adult emergence usually occurs in late June to early July. Trunk sprays need to be applied shortly after this emergence. One treatment will probably not protect you for the season. This moth has an extended emergence and flight time. Using traps (in a non-disrupted block) will allow you to monitor the population in your orchard.
Coryneum Blight - The unusual early summer rains last year brought about an unprecedented amount of coryneum blight damage. A survey of the scientific literature will reveal that once established it may take several years to remove its presence. Blight control can be summed up with one fact: Prevention not cure. Most of the materials we have for use against coryneum blight are preventative. They need to be on the plant ahead of an infection event. So, WATCH THE WEATHER! If blight damage impacted your bottom line last year, or you’ve seen the signs of infection this season, be proactive and protect your fruit BEFORE a prolonged rain event. Temperatures of 70 to 80 degrees F are optimum for Coryneum infections. Lesions can develop at 45 degrees but at a much slower rate. It takes from two to five days for a spore to initiate infection and cause a visible lesion (cull your fruit).
Protect, protect, protect!
Calcium is an extremely important mineral in many plant processes:
maintains the strength of stems and stalks
regulates the absorption of nutrients across plasma cell membranes
functions in plant cell elongation and division
functions in plant structure and permeability of cell membranes
Calcium is a secondary nutrient even though the concentration of calcium in the plant is as great as nitrogen or potassium. Calcium is nontoxic, even in high concentrations, and serves as a detoxifying agent. Calcium is a critical component of the cell wall and acts as the cement that binds the cell walls together. Calcium is one of the most significant factors of firmness with a direct correspondence to the storage and shelf life of fruit. Seed viability is also directly related to calcium concentration.
Calcium deficiencies can be observed as bitter pit in apples, blossom end rot in tomatoes and chilies, leaf tip burn in lettuce, internal brown spot in potatoes and softer, non-marketable fruit. In general, shorter fruit shelf life.
There are several causes of calcium deficiency to show up in fruit and vegetables even though soil and weather conditions seem perfect. With the application of nitrogen fertilizers, nitrogen is moved through the pipeline in the plant approximately 20 times faster than calcium. Calcium is the slowest moving nutritional mineral in the plant. High amounts of nitrogen are frequently applied in an attempt to maintain yields. This large nitrogen boost causes the plant to grow faster than the calcium can move within the plant, thus inducing calcium deficiencies in the growing points and fruit. A second reason for calcium deficiency is the passive movement of calcium through the xylem (water conducting tissue) by transpiration. Leaves have a much higher rate of transpiration than fruit, causing a lower calcium concentration in the fruit. This makes leaf calcium concentrations and appearance a poor indication of calcium levels in the fruit. One can have adequate or even high concentrations of calcium in leaf tissue analyses and still have calcium deficiencies in the fruit. On fruit that is sensitive to calcium deficiency, start early with calcium applications (pre-bloom) and continue through the season with as many applications as you can manage.