30 articles tagged "Pumpkins".

You may be seeing a few “stink bug-like” insects crawling around on your cucurbit crops this time of year. However, these slightly more slender insects are not stink bugs, they are actually squash bugs. Similarly to stink bugs though, they do give off quite an odor when crushed! Squash bug adults and nymphs (immatures) (Figures 1 – 3) attack all cucurbit vine crops, especially squash, pumpkin, cucumber, and melon. These insects feed by sticking their needle-like mouthparts into plant parts to sip on sap. Feeding damage by adults and nymphs can cause significant damage to the fruit and foliage: damaged fruits are disfigured and discolored, and leaves may wilt and become brittle and discolored as well. Generally, squash bugs are not a problem if controlled earlier in the season with insecticides. If not however, it’s still possible to see adults, nymphs, and even egg masses on plants as we move[Read More…]


Winter squash – butternut, acorn, and kabocha – in our downy mildew sentinel plot at Pinney Purdue were showing some wilted and stunted plants by late July (Figure 1). They are easily pulled up, the stem breaking off at ground level, revealing a brown stringy decayed-looking stem base (Figure 2). Sometimes there is a little whitish or maybe pinkish mold on the stem. I cut open a kabocha squash to look for squash vine borer larva and found sap beetles that seemed to be feeding inside the stem, but no vine borer (Figure 3). The sap beetles were clearly taking advantage of an opportunity, but not the cause of the wilt. Perhaps a borer had already come and gone. I used scotch tape to pick up some of the mold and put it on a slide to look at under the microscope. At 100X and 400X I saw among the[Read More…]


Bacterial spot can cause mostly light colored angular lesions on pumpkin leaves.

I have observed this disease in scattered commercial pumpkin and squash fields across Indiana. Symptoms: Bacterial spot causes ⅛-¼ inch angular leaf lesions that are white to light brown in color (Figure 1). These leaf lesions may be accompanied by yellowing (chlorosis). The more important symptom are the lesions on fruit that are scabby to raised, round and a light brown in color. These lesions are often less than ⅛ inch in diameter and do not extend into the surface of the fruit. However, lesions may become secondarily infected in which case lesions can become an inch or more in diameter. Such lesions may grow into the flesh of the fruit (Figure 2). Any type of fruit lesion can ruin the marketability of the fruit. Biology: Leaf lesions, while unimportant economically, are important in diagnosing bacterial spot before fruit is present. This head start allows growers to begin preventive measures.[Read More…]


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The wet spring has likely delayed some planting of pumpkins. What does delayed planting mean for yield? Data and observations from Purdue Ag Centers offer some perspective to supplement other experience. Figure 1 shows how pumpkin yield was affected by planting date for 6 trials. Each line represents a different trial. The Y-axis shows relative yield within in each trial. Yield of the first planting date for each trial is set to 100. For the two trials at Pinney Purdue (orange lines, PP2002 and PP2003), pumpkins seeded June 20-25 yielded 70%-85% of pumpkins seeded by early June. In the 1995-1996 trials at Southwest Purdue Ag Center (light green lines, SW1995 and SW1996), pumpkins transplanted June 25-30 produced about 50% of those transplanted two weeks earlier (June 10-15). Transplanting two weeks later (July 10-15) produced only 30% of the yield compared to the June 10-15 plantings. In the 1997-1998 trials at[Read More…]


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With the start of pumpkin harvest, it is a good time to review important considerations for harvest and postharvest storage of pumpkins and winter squash (butternut, acorn and hubbard squash etc.). Pumpkin and winter squash should be harvested fully mature to reach their optimal quality and fulfill their potential for long shelf lives. Characters indicating fruit maturity include loss of rind surface gloss, ground spot yellowing, and hardening of the skin to the level that it is resistant to puncture with a thumbnail. Except for some striped varieties, mature fruit should have solid external color. If fruit have to be harvested pre-mature because of plant decline, these fruit won’t store as well as mature fruit. The best practice is to harvest the fruit as soon as they are fully mature and then store under proper conditions. If mature fruit are left attached to the vines, it increases the chance of[Read More…]


Several pumpkin growers have asked me when to stop managing for pumpkin diseases. That is, when should a pumpkin grower stop applying fungicides? I cannot provide a definitive answer for this question; every grower will have to make his or her own decision. Below, however, are some factors to consider. Estimate the crop yield-walk through the field and evaluate the yield of pumpkins that are ready to harvest. Be sure to only consider fruit of marketable quality. If the yield is at or above what is expected, it may be time to put the sprayer away. Estimate when harvest will take place-Pumpkins that are scheduled for harvest in the next week or two are less likely to need any fungicide treatment. A longer period to final harvest may indicate that there is time for immature fruit to ripen. For example, pumpkins that are to be picked by the consumer up to Halloween may have time to mature.[Read More…]


Many of us may forget about the pesky squash vine borer until it’s too late. This pest of cucurbit crops tends to be sporadic in our region; you are either battling it every year or it hardly makes an appearance. The squash vine borer is a member of the clear-winged moths, a unique group of moths that are active during the daytime. They are very beautiful with their bright colored orange tufts on their legs (Figure 1), but can be devastating. The insect overwinters as a late instar larvae or pupa in the soil. When the weather warms, they mature and adults emerge. You can scout for the first generation of adults in the spring and should target pesticide applications at the base of the plant when adults are first spotted and for two weeks thereafter. If you wait, the eggs will hatch and the larvae will bore into the[Read More…]


Plectosporium lesions on pumpkin fruit are less common.

Before writing this article, I went back to an old article from 2015. In 2015, I had written, Plectosporium blight was more severe than normal. In 2018, I have also observed more Plectosporium blight than usual. It is not clear to me why this disease seems to be more widespread compared to recent seasons. However, it makes sense to review Plectosporium blight here. I would rank Plectosporium blight behind powdery mildew, bacterial leaf spot and Phytophthora blight in economic damage caused. The occurrence of this disease is usually sporadic. However, when it occurs, it can cause yield loss if left uncontrolled. Plectosporium blight can be recognized from the light tan spindle shaped lesions on stems and leaf petioles (Figure 1 and 2) Lesions on leaves may be dimple like. Lesions may also occur on the fruit (Figure 3), although these symptoms are less common. Yield loss is most often caused[Read More…]


Figure 3: The pumpkin plants in the foreground of this photos have yellow leaves.

This time of year, I receive many complaints of pumpkin plants with yellow leaves. There can be many reasons why pumpkin plants have yellow leaves. The most common reason for yellow pumpkin leaves doesn’t have anything to do with a disease that can spread from plant to plant. Usually, the reason for the yellow pumpkin leaves has to do with lack of water, weather that has been too hot, nutrient deficiency or other stresses. The photos and discussion below will, I hope, illustrate my point. Let’s say you have a pumpkin field where you have pumpkin leaves that are yellow and you are wondering about the cause. You may want to ask yourself, which leaves are yellow and where are they yellow. In Figure 1, yellow pumpkin leaves may be observed.  When one looks a bit closer to find out where the yellow leaves are, one can see that the[Read More…]


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One of the most common diseases of pumpkin in Indiana is powdery mildew.  Growers are naturally anxious to observe whether the fungicide they have been applying for this disease has been effective.   Therefore, many pumpkin growers scout their fields for disease. Although powdery mildew is relatively easy to recognize, it is possible to become confused.   Figure one shows two pumpkin leaves.  The bottom leaf has the white, sporulation of the powdery mildew fungus in colonies randomly scattered across the leaf.   The top leaf, has silvery coloration primarily along the vein.  This latter leaf is a healthy variegated leaf.   Some pumpkin varieties show this type of variegation more than others. It may be a good idea to study the photo shown here so that one can tell the difference between a pumpkin leaf with the disease powdery mildew and a healthy leaf that is merely variegated


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