- Dormant season oil sprays
- Dormant season copper sprays
- Dormant season urea sprays
February 17, 2022 Dave Schmitt
Early Season Tree Fruit Pest Control for 2022
June 29, 2021 Thierry Besancon
About the safe use of glufosinate and glyphosate herbicides in apple and peach orchards
Recently, New Jersey tree fruit growers have expressed concerns regarding the use of glufosinate for weed control in apple and peach orchards.
Glufosinate is a nonselective post-emergence foliar herbicide that can be used for directed applications around trees, vines, and berries. Glufosinate provides control of many annual broadleaf and grass weeds; however, control of large or well-tillered annual grasses, such as yellow or giant foxtail can be marginal. Glufosinate has no soil activity.
Work conducted by Dr. Brad Majek a few years ago indicated that direct application of glufosinate to the mature brown bark of the lower trunk may cause severe injury by killing the cambium layer at the point of contact (https://plant-pest-advisory.rutgers.edu/glufosinate-products-sold-as-rely-280-expand-as-generic-products-enter-the-market/). However, this type of injury is not systematically associated with glufosinate application as we observed it in a trial conducted in 2017 at the Snyder Research Farm on mature “Pink Lady” apple trees which were not damaged following glufosinate application (Rely 280 at 64 fl oz/A). Additionally, injury in the form of vertical cracks in the of trunk bark have also be observed on apple trees exposed to glyphosate (https://nyshs.org/wp-content/uploads/2016/10/Pages-23-28-from-NYFQ-Winter-12-12-2013.cmc_.pdf), not only to glufosinate.
As highlighted by Dr. Dave Rosenberg (retired Plant Pathologist at Cornell’s Hudson Valley Lab) on his blog (https://blogs.cornell.edu/plantpathhvl/2014/06/30/apple-summer-diseases-herbicide-problems-and-irrigation/), “NEITHER glyphosate nor glufosinate cause trunk injury to apple trees EVERY time that they are used or in every orchard in which they are applied”. Field reports suggest that injury is detected when trees are exposed to specific conditions that still need to be precisely defined. Dr. Rosenberg’s opinion is that “the potential for damage is significantly higher if tree trunks are hit with either of these herbicides during or just prior to periods of drought stress”. Under these drought conditions, “the additional desiccation from herbicide exposure may predispose the trunks to invasion by Botryosphaeria dothidea, a canker pathogen that is incapable of killing the cambium in healthy functioning trees, but which becomes very pathogenic in drought-stressed trees”. Dr. Rosenberg also suspects that similar injury can be observed on young trees following application of paraquat. Other stress factors, such as cold injury or previous bark damages, may also increase the risk of herbicide injury.
So, to safely apply glyphosate or glufosinate in peaches or apples, it is important following some guidelines that will help minimizing glyphosate or glufosinate damages to the bark:
- As specified by the label for glufosinate products and the Rutgers 2021-22 E002 Rutgers Tree Fruit guide, contact by the herbicide of parts of trees other than mature brown bark (including suckers) can result in serious damage. It is therefore especially important to protect young trees from potential glufosinate or glyphosate injury by wrapping them with grow tubes or waxed containers.
- For mature trees, the use of a shield boom is required for minimizing as much as possible contact between the herbicide spray and the tree bark. Shields will also minimize the bounce-back from bare soil that sometimes allows a haze of small droplets to drift upward into the trees.
- Avoid applications of herbicides during periods when trees are already experiencing water stress or where water-stress can be expected in the near future. Additionally, weed control efficacy of herbicides such as glyphosate of glufosinate can severely decrease when weeds are under heat stress.
- Keep the pressure as low as possible (no more than 30 psi) to minimize generation of small droplets. If not feasible, use air-induction nozzles to reduce the production of small droplets.
- Glyphosate should not be applied immediately after suckers are cut because it is readily absorbed by freshly cut stems.
Cicadas Are Here and Fruit IPM for 5/26/21
Cicadas are Here, There and Everywhere (Depending where you are): 17 year cicadas began emergence last week. These insects while a marvel in the insect world, are also capable of doing considerable damage to young fruit trees, grape vines, and blueberry bushes. After mating they begin to deposit their eggs in slits along small diameter branches. Thin branches which are loaded with fruit weight and damaged by egg laying can break. Some growers have asked about damage and what they can do to prevent it. Most egg laying is starting this week.
April 20, 2021 Dave Schmitt
Tree Fruit IPM Report for April 20, 2021
Tree Fruit Phenology:
Tree Fruit Phenology remains about normal. In southern counties most peach orchards are at petal fall. Redhaven was at approximately full bloom on 4/12, and 90% petal fall on 4/20. Plums are past petal fall and pears are at late bloom to petal fall. Red Delicious is at full bloom. Sweet cherries are at full bloom to late bloom and tart cherries are in bloom. [Read more…]
April 19, 2021 Dave Schmitt
What to Look for At Bloom: Cankers of Stone fruit.
Bacterial Spot is a key pest of Peach, Nectarine and Plum and in some years like 2019 can cause significant losses. It is caused by the bacterium Xanthomonas arbicola pv. pruni. Bacterial spot cankers that cause tip dieback (commonly called Black Tip) are often difficult to distinguish from cankers caused by other peach diseases. Other cankers that may appear during bloom are caused by the blossom blight phase of brown rot, and constriction canker. Black tip usually appears during or just after bloom. Typical symptoms are a gradual blackening of the tip with dead tissue moving down the twig and is often observed on highly susceptible cultivars (Fig. 1). Tip die back may also occur from abiotic factors such as frost. Tip die back from frost is often accompanied by blind wood usually 6-8 inches below the tip where leaves and flowers have fallen off after being killed by a freeze.
Fig. 1 Tip die back likely bacterial spot or spring frost.
In some cases the twig may appear healthy and a shoot begins growing from the tip only to die back after leafing out and flowering. This is often a symptom of late winter/early spring infections of constriction canker. Many times a bud that was infected in the fall and never leafed out may be found just below the new shoot that is dying. This usually a good clue that constriction canker is the cause. These symptoms may be more prevalent in old trees that have a history of the disease (Fig. 2).
Fig. 2 Tip die back possibly caused by constriction canker.
Tip cankers such as these may be accompanied by cankers on flower buds lower down the on the twig typically associated with blossom blight or constriction canker, or they may appear alone. Spring cankers from bacterial spot that form around flower buds are less commonly seen in our region. In cases like this it is difficult to diagnose the disease early on, especially where symptoms are randomly found at low levels or are mixed in appearance. The only thing that can be done is to note the trouble blocks and watch to see what develops. Blossom blight and constriction canker will eventually develop unique symptoms. Bacterial spot lesions will eventually show on the leaves. If you see black tip cankers forming during bloom its not a bad idea to assume its bacterial spot and include copper or oxytetracycline with your blossom blight sprays.
April 12, 2021 Dave Schmitt
Tree Fruit IPM Report for April 12, 2021
Tree Fruit Phenology:
Tree Fruit Phenology remains about normal. In southern counties all peach orchards are at full bloom to petal fall. Redhaven was at approximately full bloom on 4/12. Plums are at petal fall and pears are at full bloom. Red Delicious is at pink with just a few blossoms beginning to open. Sweet cherries are at early to full bloom and tart cherries are nearing bloom. [Read more…]
