Fruit Crops Edition

Seasonal updates on diseases, insects, weeds impacting tree fruit and small fruit (blueberry, cranberry, and wine grape). Fruit Pest Alerts are also available via this category feed.
 
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April 24, 2020

Disease Management in Cold-Injured Peach Orchards

Several recent overnight cold periods have damaged newly fertilized flowers and/or very young fruit in New Jersey peach orchards. The percent of injured fruit in any particular orchard block varies with cultivar and location. Some blocks have enough un-injured fruit to be salvaged for the growing season. Their economic return will be sufficient to warrant a continuation of standard practices.

In those orchards that lack sufficient fruit, the tendency may be to abandon the spray program. After all, these blocks will produce no revenue, so any activity will result in a net economic loss. However, this thinking is short-sited.  Without any form of control, the pathogens will use this summer as an opportunity to increase their populations and, therefore, the amount of overwintering inoculum for the 2021 season. Next year will be a struggle to control disease, especially if the weather is favorable for disease development.

In cold-injured, non-bearing orchards, the three diseases of concern are scab, bacterial spot, and brown rot. The goal will be to provide enough control for disease suppression while keeping costs to a minimum. Details for their control are presented below.

Peach Scab. Fusicladium carpophilum, the causal agent of peach scab, overwinters in twig lesions on current season fruiting wood. In southern New Jersey, spores are produced on these lesions from bloom through early July (~ mid-July in north Jersey). During rain periods, these spores are disseminated to both fruit and the current season’s vegetative shoots. So, even though fruit may not be present (or in low numbers), control is necessary to prevent build-up of shoot infections, which will provide inoculum for the 2021 season. Note these lesions will not be visible until next spring.

If control of fruit scab during the 2019 season was excellent (≤ 5% fruit infected), then this is an indication that the current number of overwintering lesions on shoots may also be low. In this case, the application of Captan 80WDG (2.5 lb/A) at shuck split (SS), first cover (1C), and second cover (2C) followed by bi-weekly sulfur (8-10 lb actual/A) sprays until early July should be sufficient for scab control this season. The captan applied from SS-2C will also control any latent brown rot infection on young green fruit (susceptible until pit-hardening at ~ 2C), assuming they are present.

If >5% of fruit were infected with scab at harvest in 2019, then the current number of overwintering lesions on shoots may also be high. In this case, applications of Flint Extra 3.8 fl oz/A (formerly Gem) at SS and 1C and Quadris Top 12 fl oz/A at 2C followed by bi-weekly sulfur sprays will provide a very strong program for scab control; this program will also manage latent brown rot infection on any green fruit present.  If Quadris Top cannot be used because the sprayer is also used on apples (phytotoxicity! see label), then substitute Captan for the Quadris Top.

An intermediate scab program can also be considered. In this case, Flint Extra is applied at SS, Captan at 1C and 2C, followed by the sulfur cover sprays every two weeks until early July.  In all of these programs, the Flint Extra acts as an anti-sporulant on the overwintering scab lesions, reducing spore production by 70% for the entire season.

Bacterial Spot. During the growing season from about petal fall onward, the bacterial spot pathogen Xanthomonas arboricola pv. pruni infects fruit, leaves, and current season vegetative shoots (summer cankers) on susceptible cultivars. Thus, the lack of fruit doesn’t prevent the occurrence of an epidemic on the foliage and shoots. If no control is applied, then a larger than usual number of infected leaves, summer cankers, and epiphytic inoculum may be present going into the post-harvest season. This higher level of inoculum may result in a greater number of spring cankers formed for the 2021 season.

Given the above scenario, some form of disease control or suppression is warranted.  Bi-weekly sprays of a copper bactericide at 0.5 oz actual (metallic) copper per acre should be sufficient. The goal is to keep inoculum levels low advancing into the post-harvest season. Oxytetracycline, applied prior to critical warm, rainy periods, could also be used. However, the expense of this antibiotic is probably not warranted given the lack of economic return from a non-bearing block.

Brown Rot. If no fruit are present, then control is not needed. In low-yielding peach blocks not destined for harvest, the main goal for brown rot control is to prevent the formation of overwintering mummies. If the brown rot pathogen Monilinia fructicola is allowed to infect and colonize fruit very quickly, then the abscission layer in the petiole may be killed. This action will thereby prevent fruit from falling naturally; the fruit remains attached, becoming a mummy.

Fruit should be marginally protected so that they mature, ripen, and fall from the tree before a significant amount of brown rot occurs. A single spray of any fungicide rated with good to excellent control (e.g., Captan, Indar, Bumper, Fontelis) applied between 9 and 18 days prior to harvest should be sufficient.

An alternative to fungicide control at preharvest would be to simply remove the mummies during the winter or 2021 pruning operation. Or the fruit could be removed earlier in the 2020 season. Either way, fruit or mummy removal eliminates the need for a preharvest brown rot spray. Early 2020 fruit removal also eliminates the possibility of scab or bacterial spot infection on any fruit that survived the cold period.

Filed Under: Tree Fruit
April 22, 2020

UPDATE: Paraquat Training for Certified Applicators NOW AVAILABLE IN SPANISH

The EPA-approved paraquat certified applicator training online module was released in Spanish yesterday. Training in either English or Spanish accessible at the link provided on paraquat product labels or http://www.usparaquattraining.com/.  You will be prompted to create a user account to take the training. Upon successful completion of the training, your online account can be accessed anytime to […]
Filed Under: Field, Forage & Livestock, Fruit, Landscape, Nursery, & Turf, Vegetable Crops
April 22, 2020

Produce Blue Book Shares USDA CARES Buy-Fresh Has Short Deadlines

USDA provides more details about the Buy Fresh program and a link to its solicitation page here.

USDA’s Buy Fresh program has tight deadlines

Filed Under: Commercial Ag Updates, Fruit, Vegetable Crops
April 21, 2020

USDA Announces Coronavirus Food Assistance Program

From usda.gov/media/press-releases on April 17, U.S. Secretary of Agriculture Sonny Perdue announced the Coronavirus Food Assistance Program (CFAP).

“The program will provide $16 billion in direct support based on actual losses for agricultural producers where prices and market supply chains have been impacted…” including $9.5 billion in aid to cattle, dairy and hog farmers, $3.9B to row/commodity crops, $2.1B for specialty crops growers, and $500 mil for “other” crops ($500 million).

The remaining $3B will be used to increase purchases of fresh produce, dairy, and meat to be distributed through “food banks, community and faith based organizations, and other non-profits serving Americans in need.”

More details about the CFAP can be found in the press release, however, as of yesterday morning, local USDA Service Centers had not yet received directions on how/where/when farmers should apply for direct assistance. They will inform local farmers as soon as the information becomes available and we will also pass on that information as soon as we have it.

Filed Under: Commercial Ag Updates, Field, Forage & Livestock, Fruit, Vegetable Crops
April 20, 2020

Integrating Management for Key Orchard Pests

 

By: Robert McDougall and Anne L. Nielsen

Integrated Pest Management (IPM) is the practice of using biological information to efficiently and effectively control pests while reducing reliance of pesticides. IPM is typically depicted as a pyramid of tactics that build on each other moving from least toxic at the bottom to most disruptive at the top. But in practice, IPM for insects in tree fruit relies primarily on application of synthetic insecticides guided by degree-day timing or trap counts. We want to flip the “IPM pyramid” around to emphasize that insecticides are the last tool for pest management and build upon other biologically-based practices.

Graphic describing management practices for orchard pests

By Anne Nielsen

The least disruptive means of pest control are cultural measures, those that seek to prevent pests from becoming problematic in the first place. These can include measures such as planting resistant cultivars, practicing good hygiene to prevent pest entry and maintaining diverse plantings in crop margins to encourage natural biological control agents (e.g. other insects that eat pests). In tree fruit, cultural control may include rootstock resistant to wooly apple aphid or removal and burning of pruned limbs and dying trees (for borer or scale management) which removes infested plant material and habitat for other pests.

For curative action, a central component of IPM programs depends on monitoring programs to identify pest species, occurrence and seasonality, and abundance. This is achieved primarily through direct sampling of plant tissue or baited traps. Regardless of the monitoring method, it must be conducted frequently, weekly at best. Monitoring can also establish biofix dates to start accumulating degree-days that when applied to models predict life stages of insects based on available heat units for development.

Upon identification of key pests within the orchard, the next action can take on a wide range of forms depending on the pest. This can include biological control measures, such as enhancing or introducing a natural enemy of the pest into the system in the hope of controlling it. Interactions between natural enemies and pests occur naturally within an orchard, but the strength of the interaction can be weakened through chemical insecticides and lead to outbreaks of pests, particularly aphids, mites, thrips, and scales. Implementation of reduced input or non-chemical methods can protect populations of natural enemies such as predators or parasitoids within the orchard and prevent a pest from becoming actionable. An example of a biological control program currently under investigation is controlling the Brown Marmorated Stink Bug with the Samurai Wasp, a tiny stingless Asian wasp which lays its eggs in BMSB eggs, preventing them from hatching and producing more Samurai Wasps instead of stink bugs.

The next IPM tool is behavioral management which changes the behavior of the insect so that less insecticide can be used. Insects, like other animals, have predicable behaviors, that once understood can be exploited for management. Two common approaches include altering insect behavior with pheromones (ie. mating disruption or attract-and-kill) or exploiting dispersal behaviors to apply targeted management (ie. border sprays). Mating disruption uses a species’ own sex pheromone to reduce mating within the orchard. This is accomplished by placing multiple dispensers containing pheromone throughout the orchard. This changes the behavior of male moths that are searching for females and results in fewer females laying eggs within the orchard (and cleaner fruit at harvest). For many insect species, including Oriental Fruit Moth and borers, no additional insecticide is needed (based on monitoring trap thresholds). Mating disruption for Oriental Fruit Moth in peaches can cost the same if not less than insecticide management and is highly effective. Mating disruption technology against borers is becoming increasingly necessary as further use restrictions change for Lorsban.

The behavioral tactic attract-and-kill places high doses of pheromone, usually an aggregation pheromone, on select trees to attract males and females (and sometimes nymphs) to a tree where they can then be killed with an insecticide. It is not believed to bring additional insects into the orchard, rather it brings those that are already there into one area. A second type of behavioral control is the use of border sprays. Many insects are often found in greater numbers in the edges of orchards because their dispersal is arrested due to visual cues provided by trees on the orchard edge. A border spray is usually defined as spraying the outer rows of orchard trees with insecticide. This tactic has shown to be very successful for controlling brown marmorated stink bug in peaches and apples, and reduces insecticide sprays by 25% relative to alternate row middle applications. Plum curculio also exhibits this behavior, and Rutgers is currently investigating whether it can be effectively controlled by spraying just the outer two rows of orchards during movement into the orchard.

IPM practices have evolved considerably in the past few decades and orchards are managed safer and more efficiently each year. Some of the IPM tactics described above may already be part of your orchard management practices. But as production cost increases are not instep with fruit prices, tactics that rely less on insecticide inputs will help protect orchard viability.

Filed Under: Tree Fruit Tagged With:
April 20, 2020

Tree Fruit IPM Report for April 21, 2020

Evaluating Freeze Damage in Tree Fruit: The subfreezing temperatures on the morning of April 17 Caused injury at varying levels across the state. Lows ranged from 27-30 in southern counties. Much is the damage is now visible. Any physiological damage that is not visible now will appear as the season progresses. A helpful guide for evaluating fruit damage can be in the Intermountain Tree Fruit Production Guide.

Tree Fruit Phenology: Tree Fruit Phenology remains advanced, but development is slowing. In southern counties all peach orchards are late bloom to early Shuck Split. Redhaven was at approximately full bloom on March 30, and was at Petal Fall by April 14. Peach bloom has been very long this year. Plums are past shuck fall. Pears are late bloom/Petal Fall. Red Delicious is pink to 50% bloom. Cherries are at 50% bloom. [Read more…]

Filed Under: Tree Fruit Tagged With: , , , ,